docs: cleanup the explanation paragraphs at the start of each exercise.

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Robert Fry 2023-05-29 18:39:08 +01:00
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95 changed files with 577 additions and 337 deletions

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@ -1,10 +1,13 @@
// clippy1.rs // clippy1.rs
// The Clippy tool is a collection of lints to analyze your code
// so you can catch common mistakes and improve your Rust code.
// //
// For these exercises the code will fail to compile when there are clippy warnings // The Clippy tool is a collection of lints to analyze your code so you can
// check clippy's suggestions from the output to solve the exercise. // catch common mistakes and improve your Rust code.
// Execute `rustlings hint clippy1` or use the `hint` watch subcommand for a hint. //
// For these exercises the code will fail to compile when there are clippy
// warnings check clippy's suggestions from the output to solve the exercise.
//
// Execute `rustlings hint clippy1` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,5 +1,7 @@
// clippy2.rs // clippy2.rs
// Execute `rustlings hint clippy2` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint clippy2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,5 +1,8 @@
// clippy3.rs // clippy3.rs
//
// Here's a couple more easy Clippy fixes, so you can see its utility. // Here's a couple more easy Clippy fixes, so you can see its utility.
//
// Execute `rustlings hint clippy3` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,7 +1,11 @@
// AsRef and AsMut allow for cheap reference-to-reference conversions. // as_ref_mut.rs
// Read more about them at https://doc.rust-lang.org/std/convert/trait.AsRef.html //
// and https://doc.rust-lang.org/std/convert/trait.AsMut.html, respectively. // AsRef and AsMut allow for cheap reference-to-reference conversions. Read more
// Execute `rustlings hint as_ref_mut` or use the `hint` watch subcommand for a hint. // about them at https://doc.rust-lang.org/std/convert/trait.AsRef.html and
// https://doc.rust-lang.org/std/convert/trait.AsMut.html, respectively.
//
// Execute `rustlings hint as_ref_mut` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,7 +1,11 @@
// The From trait is used for value-to-value conversions. // from_into.rs
// If From is implemented correctly for a type, the Into trait should work conversely. //
// You can read more about it at https://doc.rust-lang.org/std/convert/trait.From.html // The From trait is used for value-to-value conversions. If From is implemented
// Execute `rustlings hint from_into` or use the `hint` watch subcommand for a hint. // correctly for a type, the Into trait should work conversely. You can read
// more about it at https://doc.rust-lang.org/std/convert/trait.From.html
//
// Execute `rustlings hint from_into` or use the `hint` watch subcommand for a
// hint.
#[derive(Debug)] #[derive(Debug)]
struct Person { struct Person {
@ -20,20 +24,21 @@ impl Default for Person {
} }
} }
// Your task is to complete this implementation // Your task is to complete this implementation in order for the line `let p =
// in order for the line `let p = Person::from("Mark,20")` to compile // Person::from("Mark,20")` to compile Please note that you'll need to parse the
// Please note that you'll need to parse the age component into a `usize` // age component into a `usize` with something like `"4".parse::<usize>()`. The
// with something like `"4".parse::<usize>()`. The outcome of this needs to // outcome of this needs to be handled appropriately.
// be handled appropriately.
// //
// Steps: // Steps:
// 1. If the length of the provided string is 0, then return the default of Person // 1. If the length of the provided string is 0, then return the default of
// 2. Split the given string on the commas present in it // Person.
// 3. Extract the first element from the split operation and use it as the name // 2. Split the given string on the commas present in it.
// 4. If the name is empty, then return the default of Person // 3. Extract the first element from the split operation and use it as the name.
// 5. Extract the other element from the split operation and parse it into a `usize` as the age // 4. If the name is empty, then return the default of Person.
// If while parsing the age, something goes wrong, then return the default of Person // 5. Extract the other element from the split operation and parse it into a
// Otherwise, then return an instantiated Person object with the results // `usize` as the age.
// If while parsing the age, something goes wrong, then return the default of
// Person Otherwise, then return an instantiated Person object with the results
// I AM NOT DONE // I AM NOT DONE
@ -77,7 +82,8 @@ mod tests {
} }
#[test] #[test]
fn test_bad_age() { fn test_bad_age() {
// Test that "Mark,twenty" will return the default person due to an error in parsing age // Test that "Mark,twenty" will return the default person due to an
// error in parsing age
let p = Person::from("Mark,twenty"); let p = Person::from("Mark,twenty");
assert_eq!(p.name, "John"); assert_eq!(p.name, "John");
assert_eq!(p.age, 30); assert_eq!(p.age, 30);

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@ -1,10 +1,13 @@
// from_str.rs // from_str.rs
// This is similar to from_into.rs, but this time we'll implement `FromStr` //
// and return errors instead of falling back to a default value. // This is similar to from_into.rs, but this time we'll implement `FromStr` and
// Additionally, upon implementing FromStr, you can use the `parse` method // return errors instead of falling back to a default value. Additionally, upon
// on strings to generate an object of the implementor type. // implementing FromStr, you can use the `parse` method on strings to generate
// You can read more about it at https://doc.rust-lang.org/std/str/trait.FromStr.html // an object of the implementor type. You can read more about it at
// Execute `rustlings hint from_str` or use the `hint` watch subcommand for a hint. // https://doc.rust-lang.org/std/str/trait.FromStr.html
//
// Execute `rustlings hint from_str` or use the `hint` watch subcommand for a
// hint.
use std::num::ParseIntError; use std::num::ParseIntError;
use std::str::FromStr; use std::str::FromStr;
@ -33,15 +36,18 @@ enum ParsePersonError {
// Steps: // Steps:
// 1. If the length of the provided string is 0, an error should be returned // 1. If the length of the provided string is 0, an error should be returned
// 2. Split the given string on the commas present in it // 2. Split the given string on the commas present in it
// 3. Only 2 elements should be returned from the split, otherwise return an error // 3. Only 2 elements should be returned from the split, otherwise return an
// error
// 4. Extract the first element from the split operation and use it as the name // 4. Extract the first element from the split operation and use it as the name
// 5. Extract the other element from the split operation and parse it into a `usize` as the age // 5. Extract the other element from the split operation and parse it into a
// with something like `"4".parse::<usize>()` // `usize` as the age with something like `"4".parse::<usize>()`
// 6. If while extracting the name and the age something goes wrong, an error should be returned // 6. If while extracting the name and the age something goes wrong, an error
// should be returned
// If everything goes well, then return a Result of a Person object // If everything goes well, then return a Result of a Person object
// //
// As an aside: `Box<dyn Error>` implements `From<&'_ str>`. This means that if you want to return a // As an aside: `Box<dyn Error>` implements `From<&'_ str>`. This means that if
// string error message, you can do so via just using return `Err("my error message".into())`. // you want to return a string error message, you can do so via just using
// return `Err("my error message".into())`.
impl FromStr for Person { impl FromStr for Person {
type Err = ParsePersonError; type Err = ParsePersonError;

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@ -1,9 +1,13 @@
// try_from_into.rs // try_from_into.rs
// TryFrom is a simple and safe type conversion that may fail in a controlled way under some circumstances. //
// Basically, this is the same as From. The main difference is that this should return a Result type // TryFrom is a simple and safe type conversion that may fail in a controlled
// instead of the target type itself. // way under some circumstances. Basically, this is the same as From. The main
// You can read more about it at https://doc.rust-lang.org/std/convert/trait.TryFrom.html // difference is that this should return a Result type instead of the target
// Execute `rustlings hint try_from_into` or use the `hint` watch subcommand for a hint. // type itself. You can read more about it at
// https://doc.rust-lang.org/std/convert/trait.TryFrom.html
//
// Execute `rustlings hint try_from_into` or use the `hint` watch subcommand for
// a hint.
use std::convert::{TryFrom, TryInto}; use std::convert::{TryFrom, TryInto};
@ -25,14 +29,13 @@ enum IntoColorError {
// I AM NOT DONE // I AM NOT DONE
// Your task is to complete this implementation // Your task is to complete this implementation and return an Ok result of inner
// and return an Ok result of inner type Color. // type Color. You need to create an implementation for a tuple of three
// You need to create an implementation for a tuple of three integers, // integers, an array of three integers, and a slice of integers.
// an array of three integers, and a slice of integers.
// //
// Note that the implementation for tuple and array will be checked at compile time, // Note that the implementation for tuple and array will be checked at compile
// but the slice implementation needs to check the slice length! // time, but the slice implementation needs to check the slice length! Also note
// Also note that correct RGB color values must be integers in the 0..=255 range. // that correct RGB color values must be integers in the 0..=255 range.
// Tuple implementation // Tuple implementation
impl TryFrom<(i16, i16, i16)> for Color { impl TryFrom<(i16, i16, i16)> for Color {

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@ -1,10 +1,14 @@
// Type casting in Rust is done via the usage of the `as` operator. // using_as.rs
// Please note that the `as` operator is not only used when type casting.
// It also helps with renaming imports.
// //
// The goal is to make sure that the division does not fail to compile // Type casting in Rust is done via the usage of the `as` operator. Please note
// and returns the proper type. // that the `as` operator is not only used when type casting. It also helps with
// Execute `rustlings hint using_as` or use the `hint` watch subcommand for a hint. // renaming imports.
//
// The goal is to make sure that the division does not fail to compile and
// returns the proper type.
//
// Execute `rustlings hint using_as` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,4 +1,5 @@
// enums1.rs // enums1.rs
//
// No hints this time! ;) // No hints this time! ;)
// I AM NOT DONE // I AM NOT DONE

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@ -1,5 +1,7 @@
// enums2.rs // enums2.rs
// Execute `rustlings hint enums2` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint enums2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,6 +1,9 @@
// enums3.rs // enums3.rs
//
// Address all the TODOs to make the tests pass! // Address all the TODOs to make the tests pass!
// Execute `rustlings hint enums3` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint enums3` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE
@ -37,8 +40,10 @@ impl State {
} }
fn process(&mut self, message: Message) { fn process(&mut self, message: Message) {
// TODO: create a match expression to process the different message variants // TODO: create a match expression to process the different message
// Remember: When passing a tuple as a function argument, you'll need extra parentheses: fn function((t, u, p, l, e)) // variants
// Remember: When passing a tuple as a function argument, you'll need
// extra parentheses: fn function((t, u, p, l, e))
} }
} }

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@ -1,9 +1,13 @@
// errors1.rs // errors1.rs
// This function refuses to generate text to be printed on a nametag if //
// you pass it an empty string. It'd be nicer if it explained what the problem // This function refuses to generate text to be printed on a nametag if you pass
// was, instead of just sometimes returning `None`. Thankfully, Rust has a similar // it an empty string. It'd be nicer if it explained what the problem was,
// construct to `Option` that can be used to express error conditions. Let's use it! // instead of just sometimes returning `None`. Thankfully, Rust has a similar
// Execute `rustlings hint errors1` or use the `hint` watch subcommand for a hint. // construct to `Option` that can be used to express error conditions. Let's use
// it!
//
// Execute `rustlings hint errors1` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,21 +1,23 @@
// errors2.rs // errors2.rs
//
// Say we're writing a game where you can buy items with tokens. All items cost // Say we're writing a game where you can buy items with tokens. All items cost
// 5 tokens, and whenever you purchase items there is a processing fee of 1 // 5 tokens, and whenever you purchase items there is a processing fee of 1
// token. A player of the game will type in how many items they want to buy, // token. A player of the game will type in how many items they want to buy, and
// and the `total_cost` function will calculate the total cost of the tokens. // the `total_cost` function will calculate the total cost of the tokens. Since
// Since the player typed in the quantity, though, we get it as a string-- and // the player typed in the quantity, though, we get it as a string-- and they
// they might have typed anything, not just numbers! // might have typed anything, not just numbers!
//
// Right now, this function isn't handling the error case at all (and isn't // Right now, this function isn't handling the error case at all (and isn't
// handling the success case properly either). What we want to do is: // handling the success case properly either). What we want to do is: if we call
// if we call the `parse` function on a string that is not a number, that // the `parse` function on a string that is not a number, that function will
// function will return a `ParseIntError`, and in that case, we want to // return a `ParseIntError`, and in that case, we want to immediately return
// immediately return that error from our function and not try to multiply // that error from our function and not try to multiply and add.
// and add. //
// There are at least two ways to implement this that are both correct-- but one
// There are at least two ways to implement this that are both correct-- but // is a lot shorter!
// one is a lot shorter! //
// Execute `rustlings hint errors2` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint errors2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,8 +1,11 @@
// errors3.rs // errors3.rs
//
// This is a program that is trying to use a completed version of the // This is a program that is trying to use a completed version of the
// `total_cost` function from the previous exercise. It's not working though! // `total_cost` function from the previous exercise. It's not working though!
// Why not? What should we do to fix it? // Why not? What should we do to fix it?
// Execute `rustlings hint errors3` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint errors3` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,5 +1,7 @@
// errors4.rs // errors4.rs
// Execute `rustlings hint errors4` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint errors4` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,20 +1,26 @@
// errors5.rs // errors5.rs
//
// This program uses an altered version of the code from errors4. // This program uses an altered version of the code from errors4.
//
// This exercise uses some concepts that we won't get to until later in the course, like `Box` and the // This exercise uses some concepts that we won't get to until later in the
// `From` trait. It's not important to understand them in detail right now, but you can read ahead if you like. // course, like `Box` and the `From` trait. It's not important to understand
// For now, think of the `Box<dyn ???>` type as an "I want anything that does ???" type, which, given // them in detail right now, but you can read ahead if you like. For now, think
// Rust's usual standards for runtime safety, should strike you as somewhat lenient! // of the `Box<dyn ???>` type as an "I want anything that does ???" type, which,
// given Rust's usual standards for runtime safety, should strike you as
// In short, this particular use case for boxes is for when you want to own a value and you care only that it is a // somewhat lenient!
// type which implements a particular trait. To do so, The Box is declared as of type Box<dyn Trait> where Trait is the trait //
// the compiler looks for on any value used in that context. For this exercise, that context is the potential errors // In short, this particular use case for boxes is for when you want to own a
// which can be returned in a Result. // value and you care only that it is a type which implements a particular
// trait. To do so, The Box is declared as of type Box<dyn Trait> where Trait is
// What can we use to describe both errors? In other words, is there a trait which both errors implement? // the trait the compiler looks for on any value used in that context. For this
// exercise, that context is the potential errors which can be returned in a
// Execute `rustlings hint errors5` or use the `hint` watch subcommand for a hint. // Result.
//
// What can we use to describe both errors? In other words, is there a trait
// which both errors implement?
//
// Execute `rustlings hint errors5` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,12 +1,13 @@
// errors6.rs // errors6.rs
//
// Using catch-all error types like `Box<dyn error::Error>` isn't recommended // Using catch-all error types like `Box<dyn error::Error>` isn't recommended
// for library code, where callers might want to make decisions based on the // for library code, where callers might want to make decisions based on the
// error content, instead of printing it out or propagating it further. Here, // error content, instead of printing it out or propagating it further. Here, we
// we define a custom error type to make it possible for callers to decide // define a custom error type to make it possible for callers to decide what to
// what to do next when our function returns an error. // do next when our function returns an error.
//
// Execute `rustlings hint errors6` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint errors6` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,5 +1,7 @@
// functions1.rs // functions1.rs
// Execute `rustlings hint functions1` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint functions1` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,5 +1,7 @@
// functions2.rs // functions2.rs
// Execute `rustlings hint functions2` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint functions2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,5 +1,7 @@
// functions3.rs // functions3.rs
// Execute `rustlings hint functions3` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint functions3` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,11 +1,12 @@
// functions4.rs // functions4.rs
// Execute `rustlings hint functions4` or use the `hint` watch subcommand for a hint. //
// This store is having a sale where if the price is an even number, you get 10
// This store is having a sale where if the price is an even number, you get // Rustbucks off, but if it's an odd number, it's 3 Rustbucks off. (Don't worry
// 10 Rustbucks off, but if it's an odd number, it's 3 Rustbucks off. // about the function bodies themselves, we're only interested in the signatures
// (Don't worry about the function bodies themselves, we're only interested // for now. If anything, this is a good way to peek ahead to future exercises!)
// in the signatures for now. If anything, this is a good way to peek ahead //
// to future exercises!) // Execute `rustlings hint functions4` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,5 +1,7 @@
// functions5.rs // functions5.rs
// Execute `rustlings hint functions5` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint functions5` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,7 +1,10 @@
// This shopping list program isn't compiling! // generics1.rs
// Use your knowledge of generics to fix it. //
// This shopping list program isn't compiling! Use your knowledge of generics to
// Execute `rustlings hint generics1` or use the `hint` watch subcommand for a hint. // fix it.
//
// Execute `rustlings hint generics1` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,7 +1,10 @@
// generics2.rs
//
// This powerful wrapper provides the ability to store a positive integer value. // This powerful wrapper provides the ability to store a positive integer value.
// Rewrite it using generics so that it supports wrapping ANY type. // Rewrite it using generics so that it supports wrapping ANY type.
//
// Execute `rustlings hint generics2` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint generics2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,14 +1,15 @@
// hashmaps1.rs // hashmaps1.rs
// A basket of fruits in the form of a hash map needs to be defined. //
// The key represents the name of the fruit and the value represents // A basket of fruits in the form of a hash map needs to be defined. The key
// how many of that particular fruit is in the basket. You have to put // represents the name of the fruit and the value represents how many of that
// at least three different types of fruits (e.g apple, banana, mango) // particular fruit is in the basket. You have to put at least three different
// in the basket and the total count of all the fruits should be at // types of fruits (e.g apple, banana, mango) in the basket and the total count
// least five. // of all the fruits should be at least five.
// //
// Make me compile and pass the tests! // Make me compile and pass the tests!
// //
// Execute `rustlings hint hashmaps1` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint hashmaps1` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,17 +1,18 @@
// hashmaps2.rs // hashmaps2.rs
// We're collecting different fruits to bake a delicious fruit cake. //
// For this, we have a basket, which we'll represent in the form of a hash // We're collecting different fruits to bake a delicious fruit cake. For this,
// map. The key represents the name of each fruit we collect and the value // we have a basket, which we'll represent in the form of a hash map. The key
// represents how many of that particular fruit we have collected. // represents the name of each fruit we collect and the value represents how
// Three types of fruits - Apple (4), Mango (2) and Lychee (5) are already // many of that particular fruit we have collected. Three types of fruits -
// in the basket hash map. // Apple (4), Mango (2) and Lychee (5) are already in the basket hash map. You
// You must add fruit to the basket so that there is at least // must add fruit to the basket so that there is at least one of each kind and
// one of each kind and more than 11 in total - we have a lot of mouths to feed. // more than 11 in total - we have a lot of mouths to feed. You are not allowed
// You are not allowed to insert any more of these fruits! // to insert any more of these fruits!
// //
// Make me pass the tests! // Make me pass the tests!
// //
// Execute `rustlings hint hashmaps2` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint hashmaps2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE
@ -36,9 +37,9 @@ fn fruit_basket(basket: &mut HashMap<Fruit, u32>) {
]; ];
for fruit in fruit_kinds { for fruit in fruit_kinds {
// TODO: Insert new fruits if they are not already present in the basket. // TODO: Insert new fruits if they are not already present in the
// Note that you are not allowed to put any type of fruit that's already // basket. Note that you are not allowed to put any type of fruit that's
// present! // already present!
} }
} }

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@ -1,18 +1,18 @@
// hashmaps3.rs // hashmaps3.rs
//
// A list of scores (one per line) of a soccer match is given. Each line // A list of scores (one per line) of a soccer match is given. Each line is of
// is of the form : // the form : "<team_1_name>,<team_2_name>,<team_1_goals>,<team_2_goals>"
// <team_1_name>,<team_2_name>,<team_1_goals>,<team_2_goals>
// Example: England,France,4,2 (England scored 4 goals, France 2). // Example: England,France,4,2 (England scored 4 goals, France 2).
//
// You have to build a scores table containing the name of the team, goals // You have to build a scores table containing the name of the team, goals the
// the team scored, and goals the team conceded. One approach to build // team scored, and goals the team conceded. One approach to build the scores
// the scores table is to use a Hashmap. The solution is partially // table is to use a Hashmap. The solution is partially written to use a
// written to use a Hashmap, complete it to pass the test. // Hashmap, complete it to pass the test.
//
// Make me pass the tests! // Make me pass the tests!
//
// Execute `rustlings hint hashmaps3` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint hashmaps3` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,4 +1,5 @@
// if1.rs // if1.rs
//
// Execute `rustlings hint if1` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint if1` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,7 +1,8 @@
// if2.rs // if2.rs
//
// Step 1: Make me compile! // Step 1: Make me compile!
// Step 2: Get the bar_for_fuzz and default_to_baz tests passing! // Step 2: Get the bar_for_fuzz and default_to_baz tests passing!
//
// Execute `rustlings hint if2` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint if2` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,13 +1,17 @@
// intro1.rs // intro1.rs
//
// About this `I AM NOT DONE` thing: // About this `I AM NOT DONE` thing:
// We sometimes encourage you to keep trying things on a given exercise, even // We sometimes encourage you to keep trying things on a given exercise, even
// after you already figured it out. If you got everything working and feel // after you already figured it out. If you got everything working and feel
// ready for the next exercise, remove the `I AM NOT DONE` comment below. // ready for the next exercise, remove the `I AM NOT DONE` comment below.
// Execute `rustlings hint intro1` or use the `hint` watch subcommand for a hint.
// //
// If you're running this using `rustlings watch`: The exercise file will be reloaded // If you're running this using `rustlings watch`: The exercise file will be
// when you change one of the lines below! Try adding a `println!` line, or try changing // reloaded when you change one of the lines below! Try adding a `println!`
// what it outputs in your terminal. Try removing a semicolon and see what happens! // line, or try changing what it outputs in your terminal. Try removing a
// semicolon and see what happens!
//
// Execute `rustlings hint intro1` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,6 +1,9 @@
// intro2.rs // intro2.rs
//
// Make the code print a greeting to the world. // Make the code print a greeting to the world.
// Execute `rustlings hint intro2` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint intro2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,12 +1,13 @@
// iterators1.rs // iterators1.rs
// //
// When performing operations on elements within a collection, iterators are
// essential. This module helps you get familiar with the structure of using an
// iterator and how to go through elements within an iterable collection.
//
// Make me compile by filling in the `???`s // Make me compile by filling in the `???`s
// //
// When performing operations on elements within a collection, iterators are essential. // Execute `rustlings hint iterators1` or use the `hint` watch subcommand for a
// This module helps you get familiar with the structure of using an iterator and // hint.
// how to go through elements within an iterable collection.
//
// Execute `rustlings hint iterators1` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,7 +1,10 @@
// iterators2.rs // iterators2.rs
//
// In this exercise, you'll learn some of the unique advantages that iterators // In this exercise, you'll learn some of the unique advantages that iterators
// can offer. Follow the steps to complete the exercise. // can offer. Follow the steps to complete the exercise.
// Execute `rustlings hint iterators2` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint iterators2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,10 +1,13 @@
// iterators3.rs // iterators3.rs
// This is a bigger exercise than most of the others! You can do it! //
// Here is your mission, should you choose to accept it: // This is a bigger exercise than most of the others! You can do it! Here is
// your mission, should you choose to accept it:
// 1. Complete the divide function to get the first four tests to pass. // 1. Complete the divide function to get the first four tests to pass.
// 2. Get the remaining tests to pass by completing the result_with_list and // 2. Get the remaining tests to pass by completing the result_with_list and
// list_of_results functions. // list_of_results functions.
// Execute `rustlings hint iterators3` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint iterators3` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE
@ -26,14 +29,16 @@ pub fn divide(a: i32, b: i32) -> Result<i32, DivisionError> {
todo!(); todo!();
} }
// Complete the function and return a value of the correct type so the test passes. // Complete the function and return a value of the correct type so the test
// passes.
// Desired output: Ok([1, 11, 1426, 3]) // Desired output: Ok([1, 11, 1426, 3])
fn result_with_list() -> () { fn result_with_list() -> () {
let numbers = vec![27, 297, 38502, 81]; let numbers = vec![27, 297, 38502, 81];
let division_results = numbers.into_iter().map(|n| divide(n, 27)); let division_results = numbers.into_iter().map(|n| divide(n, 27));
} }
// Complete the function and return a value of the correct type so the test passes. // Complete the function and return a value of the correct type so the test
// passes.
// Desired output: [Ok(1), Ok(11), Ok(1426), Ok(3)] // Desired output: [Ok(1), Ok(11), Ok(1426), Ok(3)]
fn list_of_results() -> () { fn list_of_results() -> () {
let numbers = vec![27, 297, 38502, 81]; let numbers = vec![27, 297, 38502, 81];

View file

@ -1,5 +1,7 @@
// iterators4.rs // iterators4.rs
// Execute `rustlings hint iterators4` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint iterators4` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,4 +1,5 @@
// iterators5.rs // iterators5.rs
//
// Let's define a simple model to track Rustlings exercise progress. Progress // Let's define a simple model to track Rustlings exercise progress. Progress
// will be modelled using a hash map. The name of the exercise is the key and // will be modelled using a hash map. The name of the exercise is the key and
// the progress is the value. Two counting functions were created to count the // the progress is the value. Two counting functions were created to count the
@ -6,7 +7,9 @@
// functionality using iterators. Try not to use imperative loops (for, while). // functionality using iterators. Try not to use imperative loops (for, while).
// Only the two iterator methods (count_iterator and count_collection_iterator) // Only the two iterator methods (count_iterator and count_collection_iterator)
// need to be modified. // need to be modified.
// Execute `rustlings hint iterators5` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint iterators5` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,11 +1,12 @@
// lifetimes1.rs // lifetimes1.rs
// //
// The Rust compiler needs to know how to check whether supplied references are // The Rust compiler needs to know how to check whether supplied references are
// valid, so that it can let the programmer know if a reference is at risk // valid, so that it can let the programmer know if a reference is at risk of
// of going out of scope before it is used. Remember, references are borrows // going out of scope before it is used. Remember, references are borrows and do
// and do not own their own data. What if their owner goes out of scope? // not own their own data. What if their owner goes out of scope?
// //
// Execute `rustlings hint lifetimes1` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint lifetimes1` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,10 +1,10 @@
// lifetimes2.rs // lifetimes2.rs
// //
// So if the compiler is just validating the references passed // So if the compiler is just validating the references passed to the annotated
// to the annotated parameters and the return type, what do // parameters and the return type, what do we need to change?
// we need to change?
// //
// Execute `rustlings hint lifetimes2` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint lifetimes2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -2,7 +2,8 @@
// //
// Lifetimes are also needed when structs hold references. // Lifetimes are also needed when structs hold references.
// //
// Execute `rustlings hint lifetimes3` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint lifetimes3` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,5 +1,7 @@
// macros1.rs // macros1.rs
// Execute `rustlings hint macros1` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint macros1` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,5 +1,7 @@
// macros2.rs // macros2.rs
// Execute `rustlings hint macros2` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint macros2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,6 +1,9 @@
// macros3.rs // macros3.rs
//
// Make me compile, without taking the macro out of the module! // Make me compile, without taking the macro out of the module!
// Execute `rustlings hint macros3` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint macros3` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,5 +1,7 @@
// macros4.rs // macros4.rs
// Execute `rustlings hint macros4` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint macros4` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,5 +1,7 @@
// modules1.rs // modules1.rs
// Execute `rustlings hint modules1` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint modules1` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,7 +1,11 @@
// modules2.rs // modules2.rs
// You can bring module paths into scopes and provide new names for them with the //
// 'use' and 'as' keywords. Fix these 'use' statements to make the code compile. // You can bring module paths into scopes and provide new names for them with
// Execute `rustlings hint modules2` or use the `hint` watch subcommand for a hint. // the 'use' and 'as' keywords. Fix these 'use' statements to make the code
// compile.
//
// Execute `rustlings hint modules2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,9 +1,12 @@
// modules3.rs // modules3.rs
// You can use the 'use' keyword to bring module paths from modules from anywhere //
// and especially from the Rust standard library into your scope. // You can use the 'use' keyword to bring module paths from modules from
// Bring SystemTime and UNIX_EPOCH // anywhere and especially from the Rust standard library into your scope. Bring
// from the std::time module. Bonus style points if you can do it with one line! // SystemTime and UNIX_EPOCH from the std::time module. Bonus style points if
// Execute `rustlings hint modules3` or use the `hint` watch subcommand for a hint. // you can do it with one line!
//
// Execute `rustlings hint modules3` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,5 +1,7 @@
// move_semantics1.rs // move_semantics1.rs
// Execute `rustlings hint move_semantics1` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint move_semantics1` or use the `hint` watch subcommand
// for a hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,9 +1,11 @@
// move_semantics2.rs // move_semantics2.rs
// Execute `rustlings hint move_semantics2` or use the `hint` watch subcommand for a hint. //
// Expected output: // Expected output:
// vec0 has length 3 content `[22, 44, 66]` // vec0 has length 3 content `[22, 44, 66]`
// vec1 has length 4 content `[22, 44, 66, 88]` // vec1 has length 4 content `[22, 44, 66, 88]`
//
// Execute `rustlings hint move_semantics2` or use the `hint` watch subcommand
// for a hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,7 +1,10 @@
// move_semantics3.rs // move_semantics3.rs
// Make me compile without adding new lines-- just changing existing lines! //
// (no lines with multiple semicolons necessary!) // Make me compile without adding new lines-- just changing existing lines! (no
// Execute `rustlings hint move_semantics3` or use the `hint` watch subcommand for a hint. // lines with multiple semicolons necessary!)
//
// Execute `rustlings hint move_semantics3` or use the `hint` watch subcommand
// for a hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,8 +1,11 @@
// move_semantics4.rs // move_semantics4.rs
// Refactor this code so that instead of passing `vec0` into the `fill_vec` function, //
// the Vector gets created in the function itself and passed back to the main // Refactor this code so that instead of passing `vec0` into the `fill_vec`
// function. // function, the Vector gets created in the function itself and passed back to
// Execute `rustlings hint move_semantics4` or use the `hint` watch subcommand for a hint. // the main function.
//
// Execute `rustlings hint move_semantics4` or use the `hint` watch subcommand
// for a hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,7 +1,10 @@
// move_semantics5.rs // move_semantics5.rs
// Make me compile only by reordering the lines in `main()`, but without //
// adding, changing or removing any of them. // Make me compile only by reordering the lines in `main()`, but without adding,
// Execute `rustlings hint move_semantics5` or use the `hint` watch subcommand for a hint. // changing or removing any of them.
//
// Execute `rustlings hint move_semantics5` or use the `hint` watch subcommand
// for a hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,6 +1,9 @@
// move_semantics6.rs // move_semantics6.rs
// Execute `rustlings hint move_semantics6` or use the `hint` watch subcommand for a hint. //
// You can't change anything except adding or removing references. // You can't change anything except adding or removing references.
//
// Execute `rustlings hint move_semantics6` or use the `hint` watch subcommand
// for a hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,5 +1,7 @@
// options1.rs // options1.rs
// Execute `rustlings hint options1` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint options1` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE
@ -7,8 +9,9 @@
// If it's before 10PM, there's 5 pieces left. At 10PM, someone eats them // If it's before 10PM, there's 5 pieces left. At 10PM, someone eats them
// all, so there'll be no more left :( // all, so there'll be no more left :(
fn maybe_icecream(time_of_day: u16) -> Option<u16> { fn maybe_icecream(time_of_day: u16) -> Option<u16> {
// We use the 24-hour system here, so 10PM is a value of 22 and 12AM is a value of 0 // We use the 24-hour system here, so 10PM is a value of 22 and 12AM is a
// The Option output should gracefully handle cases where time_of_day > 23. // value of 0 The Option output should gracefully handle cases where
// time_of_day > 23.
// TODO: Complete the function body - remember to return an Option! // TODO: Complete the function body - remember to return an Option!
??? ???
} }
@ -28,7 +31,8 @@ mod tests {
#[test] #[test]
fn raw_value() { fn raw_value() {
// TODO: Fix this test. How do you get at the value contained in the Option? // TODO: Fix this test. How do you get at the value contained in the
// Option?
let icecreams = maybe_icecream(12); let icecreams = maybe_icecream(12);
assert_eq!(icecreams, 5); assert_eq!(icecreams, 5);
} }

View file

@ -1,5 +1,7 @@
// options2.rs // options2.rs
// Execute `rustlings hint options2` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint options2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE
@ -27,8 +29,9 @@ mod tests {
let mut cursor = range; let mut cursor = range;
// TODO: make this a while let statement - remember that vector.pop also adds another layer of Option<T> // TODO: make this a while let statement - remember that vector.pop also
// You can stack `Option<T>`s into while let and if let // adds another layer of Option<T>. You can stack `Option<T>`s into
// while let and if let.
integer = optional_integers.pop() { integer = optional_integers.pop() {
assert_eq!(integer, cursor); assert_eq!(integer, cursor);
cursor -= 1; cursor -= 1;

View file

@ -1,5 +1,7 @@
// options3.rs // options3.rs
// Execute `rustlings hint options3` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint options3` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,6 +1,10 @@
// primitive_types1.rs // primitive_types1.rs
// Fill in the rest of the line that has code missing! //
// No hints, there's no tricks, just get used to typing these :) // Fill in the rest of the line that has code missing! No hints, there's no
// tricks, just get used to typing these :)
//
// Execute `rustlings hint primitive_types1` or use the `hint` watch subcommand
// for a hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,6 +1,10 @@
// primitive_types2.rs // primitive_types2.rs
// Fill in the rest of the line that has code missing! //
// No hints, there's no tricks, just get used to typing these :) // Fill in the rest of the line that has code missing! No hints, there's no
// tricks, just get used to typing these :)
//
// Execute `rustlings hint primitive_types2` or use the `hint` watch subcommand
// for a hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,6 +1,9 @@
// primitive_types3.rs // primitive_types3.rs
//
// Create an array with at least 100 elements in it where the ??? is. // Create an array with at least 100 elements in it where the ??? is.
// Execute `rustlings hint primitive_types3` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint primitive_types3` or use the `hint` watch subcommand
// for a hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,6 +1,9 @@
// primitive_types4.rs // primitive_types4.rs
//
// Get a slice out of Array a where the ??? is so that the test passes. // Get a slice out of Array a where the ??? is so that the test passes.
// Execute `rustlings hint primitive_types4` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint primitive_types4` or use the `hint` watch subcommand
// for a hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,6 +1,9 @@
// primitive_types5.rs // primitive_types5.rs
//
// Destructure the `cat` tuple so that the println will work. // Destructure the `cat` tuple so that the println will work.
// Execute `rustlings hint primitive_types5` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint primitive_types5` or use the `hint` watch subcommand
// for a hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,7 +1,10 @@
// primitive_types6.rs // primitive_types6.rs
// Use a tuple index to access the second element of `numbers`. //
// You can put the expression for the second element where ??? is so that the test passes. // Use a tuple index to access the second element of `numbers`. You can put the
// Execute `rustlings hint primitive_types6` or use the `hint` watch subcommand for a hint. // expression for the second element where ??? is so that the test passes.
//
// Execute `rustlings hint primitive_types6` or use the `hint` watch subcommand
// for a hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,14 +1,17 @@
// quiz1.rs // quiz1.rs
//
// This is a quiz for the following sections: // This is a quiz for the following sections:
// - Variables // - Variables
// - Functions // - Functions
// - If // - If
//
// Mary is buying apples. The price of an apple is calculated as follows: // Mary is buying apples. The price of an apple is calculated as follows:
// - An apple costs 2 rustbucks. // - An apple costs 2 rustbucks.
// - If Mary buys more than 40 apples, each apple only costs 1 rustbuck! // - If Mary buys more than 40 apples, each apple only costs 1 rustbuck!
// Write a function that calculates the price of an order of apples given // Write a function that calculates the price of an order of apples given the
// the quantity bought. No hints this time! // quantity bought. No hints this time!
//
// No hints this time ;)
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,14 +1,15 @@
// quiz2.rs // quiz2.rs
//
// This is a quiz for the following sections: // This is a quiz for the following sections:
// - Strings // - Strings
// - Vecs // - Vecs
// - Move semantics // - Move semantics
// - Modules // - Modules
// - Enums // - Enums
//
// Let's build a little machine in the form of a function. // Let's build a little machine in the form of a function. As input, we're going
// As input, we're going to give a list of strings and commands. These commands // to give a list of strings and commands. These commands determine what action
// determine what action is going to be applied to the string. It can either be: // is going to be applied to the string. It can either be:
// - Uppercase the string // - Uppercase the string
// - Trim the string // - Trim the string
// - Append "bar" to the string a specified amount of times // - Append "bar" to the string a specified amount of times
@ -16,6 +17,7 @@
// - The input is going to be a Vector of a 2-length tuple, // - The input is going to be a Vector of a 2-length tuple,
// the first element is the string, the second one is the command. // the first element is the string, the second one is the command.
// - The output element is going to be a Vector of strings. // - The output element is going to be a Vector of strings.
//
// No hints this time! // No hints this time!
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,17 +1,19 @@
// quiz3.rs // quiz3.rs
//
// This quiz tests: // This quiz tests:
// - Generics // - Generics
// - Traits // - Traits
// An imaginary magical school has a new report card generation system written in Rust! //
// Currently the system only supports creating report cards where the student's grade // An imaginary magical school has a new report card generation system written
// is represented numerically (e.g. 1.0 -> 5.5). // in Rust! Currently the system only supports creating report cards where the
// However, the school also issues alphabetical grades (A+ -> F-) and needs // student's grade is represented numerically (e.g. 1.0 -> 5.5). However, the
// to be able to print both types of report card! // school also issues alphabetical grades (A+ -> F-) and needs to be able to
// print both types of report card!
//
// Make the necessary code changes in the struct ReportCard and the impl block // Make the necessary code changes in the struct ReportCard and the impl block
// to support alphabetical report cards. Change the Grade in the second test to "A+" // to support alphabetical report cards. Change the Grade in the second test to
// to show that your changes allow alphabetical grades. // "A+" to show that your changes allow alphabetical grades.
//
// Execute `rustlings hint quiz3` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint quiz3` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,21 +1,24 @@
// arc1.rs // arc1.rs
// In this exercise, we are given a Vec of u32 called "numbers" with values ranging //
// from 0 to 99 -- [ 0, 1, 2, ..., 98, 99 ] // In this exercise, we are given a Vec of u32 called "numbers" with values
// We would like to use this set of numbers within 8 different threads simultaneously. // ranging from 0 to 99 -- [ 0, 1, 2, ..., 98, 99 ] We would like to use this
// Each thread is going to get the sum of every eighth value, with an offset. // set of numbers within 8 different threads simultaneously. Each thread is
// going to get the sum of every eighth value, with an offset.
//
// The first thread (offset 0), will sum 0, 8, 16, ... // The first thread (offset 0), will sum 0, 8, 16, ...
// The second thread (offset 1), will sum 1, 9, 17, ... // The second thread (offset 1), will sum 1, 9, 17, ...
// The third thread (offset 2), will sum 2, 10, 18, ... // The third thread (offset 2), will sum 2, 10, 18, ...
// ... // ...
// The eighth thread (offset 7), will sum 7, 15, 23, ... // The eighth thread (offset 7), will sum 7, 15, 23, ...
//
// Because we are using threads, our values need to be thread-safe. Therefore, // Because we are using threads, our values need to be thread-safe. Therefore,
// we are using Arc. We need to make a change in each of the two TODOs. // we are using Arc. We need to make a change in each of the two TODOs.
//
// Make this code compile by filling in a value for `shared_numbers` where the // Make this code compile by filling in a value for `shared_numbers` where the
// first TODO comment is, and create an initial binding for `child_numbers` // first TODO comment is, and create an initial binding for `child_numbers`
// where the second TODO comment is. Try not to create any copies of the `numbers` Vec! // where the second TODO comment is. Try not to create any copies of the
// `numbers` Vec!
//
// Execute `rustlings hint arc1` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint arc1` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE // I AM NOT DONE

View file

@ -1,13 +1,15 @@
// box1.rs // box1.rs
// //
// At compile time, Rust needs to know how much space a type takes up. This becomes problematic // At compile time, Rust needs to know how much space a type takes up. This
// for recursive types, where a value can have as part of itself another value of the same type. // becomes problematic for recursive types, where a value can have as part of
// To get around the issue, we can use a `Box` - a smart pointer used to store data on the heap, // itself another value of the same type. To get around the issue, we can use a
// which also allows us to wrap a recursive type. // `Box` - a smart pointer used to store data on the heap, which also allows us
// to wrap a recursive type.
// //
// The recursive type we're implementing in this exercise is the `cons list` - a data structure // The recursive type we're implementing in this exercise is the `cons list` - a
// frequently found in functional programming languages. Each item in a cons list contains two // data structure frequently found in functional programming languages. Each
// elements: the value of the current item and the next item. The last item is a value called `Nil`. // item in a cons list contains two elements: the value of the current item and
// the next item. The last item is a value called `Nil`.
// //
// Step 1: use a `Box` in the enum definition to make the code compile // Step 1: use a `Box` in the enum definition to make the code compile
// Step 2: create both empty and non-empty cons lists by replacing `todo!()` // Step 2: create both empty and non-empty cons lists by replacing `todo!()`

View file

@ -1,12 +1,16 @@
// cow1.rs // cow1.rs
//
// This exercise explores the Cow, or Clone-On-Write type. // This exercise explores the Cow, or Clone-On-Write type. Cow is a
// Cow is a clone-on-write smart pointer. // clone-on-write smart pointer. It can enclose and provide immutable access to
// It can enclose and provide immutable access to borrowed data, and clone the data lazily when mutation or ownership is required. // borrowed data, and clone the data lazily when mutation or ownership is
// The type is designed to work with general borrowed data via the Borrow trait. // required. The type is designed to work with general borrowed data via the
// Borrow trait.
// //
// This exercise is meant to show you what to expect when passing data to Cow. // This exercise is meant to show you what to expect when passing data to Cow.
// Fix the unit tests by checking for Cow::Owned(_) and Cow::Borrowed(_) at the TODO markers. // Fix the unit tests by checking for Cow::Owned(_) and Cow::Borrowed(_) at the
// TODO markers.
//
// Execute `rustlings hint cow1` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE // I AM NOT DONE
@ -50,10 +54,9 @@ mod tests {
#[test] #[test]
fn owned_no_mutation() -> Result<(), &'static str> { fn owned_no_mutation() -> Result<(), &'static str> {
// We can also pass `slice` without `&` so Cow owns it directly. // We can also pass `slice` without `&` so Cow owns it directly. In this
// In this case no mutation occurs and thus also no clone, // case no mutation occurs and thus also no clone, but the result is
// but the result is still owned because it was never borrowed // still owned because it was never borrowed or mutated.
// or mutated.
let slice = vec![0, 1, 2]; let slice = vec![0, 1, 2];
let mut input = Cow::from(slice); let mut input = Cow::from(slice);
match abs_all(&mut input) { match abs_all(&mut input) {
@ -63,9 +66,9 @@ mod tests {
#[test] #[test]
fn owned_mutation() -> Result<(), &'static str> { fn owned_mutation() -> Result<(), &'static str> {
// Of course this is also the case if a mutation does occur. // Of course this is also the case if a mutation does occur. In this
// In this case the call to `to_mut()` returns a reference to // case the call to `to_mut()` returns a reference to the same data as
// the same data as before. // before.
let slice = vec![-1, 0, 1]; let slice = vec![-1, 0, 1];
let mut input = Cow::from(slice); let mut input = Cow::from(slice);
match abs_all(&mut input) { match abs_all(&mut input) {

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@ -1,9 +1,14 @@
// rc1.rs // rc1.rs
// In this exercise, we want to express the concept of multiple owners via the Rc<T> type. //
// This is a model of our solar system - there is a Sun type and multiple Planets. // In this exercise, we want to express the concept of multiple owners via the
// The Planets take ownership of the sun, indicating that they revolve around the sun. // Rc<T> type. This is a model of our solar system - there is a Sun type and
// multiple Planets. The Planets take ownership of the sun, indicating that they
// Make this code compile by using the proper Rc primitives to express that the sun has multiple owners. // revolve around the sun.
//
// Make this code compile by using the proper Rc primitives to express that the
// sun has multiple owners.
//
// Execute `rustlings hint rc1` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,6 +1,9 @@
// strings1.rs // strings1.rs
//
// Make me compile without changing the function signature! // Make me compile without changing the function signature!
// Execute `rustlings hint strings1` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint strings1` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,6 +1,9 @@
// strings2.rs // strings2.rs
//
// Make me compile without changing the function signature! // Make me compile without changing the function signature!
// Execute `rustlings hint strings2` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint strings2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,5 +1,7 @@
// strings3.rs // strings3.rs
// Execute `rustlings hint strings3` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint strings3` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,9 +1,10 @@
// strings4.rs // strings4.rs
//
// Ok, here are a bunch of values-- some are `String`s, some are `&str`s. Your // Ok, here are a bunch of values-- some are `String`s, some are `&str`s. Your
// task is to call one of these two functions on each value depending on what // task is to call one of these two functions on each value depending on what
// you think each value is. That is, add either `string_slice` or `string` // you think each value is. That is, add either `string_slice` or `string`
// before the parentheses on each line. If you're right, it will compile! // before the parentheses on each line. If you're right, it will compile!
//
// No hints this time! // No hints this time!
// I AM NOT DONE // I AM NOT DONE

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@ -1,6 +1,9 @@
// structs1.rs // structs1.rs
//
// Address all the TODOs to make the tests pass! // Address all the TODOs to make the tests pass!
// Execute `rustlings hint structs1` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint structs1` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,6 +1,9 @@
// structs2.rs // structs2.rs
//
// Address all the TODOs to make the tests pass! // Address all the TODOs to make the tests pass!
// Execute `rustlings hint structs2` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint structs2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,8 +1,11 @@
// structs3.rs // structs3.rs
//
// Structs contain data, but can also have logic. In this exercise we have // Structs contain data, but can also have logic. In this exercise we have
// defined the Package struct and we want to test some logic attached to it. // defined the Package struct and we want to test some logic attached to it.
// Make the code compile and the tests pass! // Make the code compile and the tests pass!
// Execute `rustlings hint structs3` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint structs3` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,11 +1,14 @@
// tests1.rs // tests1.rs
// Tests are important to ensure that your code does what you think it should do. //
// Tests can be run on this file with the following command: // Tests are important to ensure that your code does what you think it should
// rustlings run tests1 // do. Tests can be run on this file with the following command: rustlings run
// tests1
// This test has a problem with it -- make the test compile! Make the test //
// pass! Make the test fail! // This test has a problem with it -- make the test compile! Make the test pass!
// Execute `rustlings hint tests1` or use the `hint` watch subcommand for a hint. // Make the test fail!
//
// Execute `rustlings hint tests1` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,7 +1,10 @@
// tests2.rs // tests2.rs
// This test has a problem with it -- make the test compile! Make the test //
// pass! Make the test fail! // This test has a problem with it -- make the test compile! Make the test pass!
// Execute `rustlings hint tests2` or use the `hint` watch subcommand for a hint. // Make the test fail!
//
// Execute `rustlings hint tests2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,8 +1,11 @@
// tests3.rs // tests3.rs
//
// This test isn't testing our function -- make it do that in such a way that // This test isn't testing our function -- make it do that in such a way that
// the test passes. Then write a second test that tests whether we get the result // the test passes. Then write a second test that tests whether we get the
// we expect to get when we call `is_even(5)`. // result we expect to get when we call `is_even(5)`.
// Execute `rustlings hint tests3` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint tests3` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,6 +1,9 @@
// tests4.rs // tests4.rs
//
// Make sure that we're testing for the correct conditions! // Make sure that we're testing for the correct conditions!
// Execute `rustlings hint tests4` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint tests4` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,10 +1,12 @@
// threads1.rs // threads1.rs
// Execute `rustlings hint threads1` or use the `hint` watch subcommand for a hint. //
// This program spawns multiple threads that each run for at least 250ms, and
// This program spawns multiple threads that each run for at least 250ms, // each thread returns how much time they took to complete. The program should
// and each thread returns how much time they took to complete. // wait until all the spawned threads have finished and should collect their
// The program should wait until all the spawned threads have finished and // return values into a vector.
// should collect their return values into a vector. //
// Execute `rustlings hint threads1` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,7 +1,11 @@
// threads2.rs // threads2.rs
// Execute `rustlings hint threads2` or use the `hint` watch subcommand for a hint. //
// Building on the last exercise, we want all of the threads to complete their work but this time // Building on the last exercise, we want all of the threads to complete their
// the spawned threads need to be in charge of updating a shared value: JobStatus.jobs_completed // work but this time the spawned threads need to be in charge of updating a
// shared value: JobStatus.jobs_completed
//
// Execute `rustlings hint threads2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE
@ -27,8 +31,9 @@ fn main() {
} }
for handle in handles { for handle in handles {
handle.join().unwrap(); handle.join().unwrap();
// TODO: Print the value of the JobStatus.jobs_completed. Did you notice anything // TODO: Print the value of the JobStatus.jobs_completed. Did you notice
// interesting in the output? Do you have to 'join' on all the handles? // anything interesting in the output? Do you have to 'join' on all the
// handles?
println!("jobs completed {}", ???); println!("jobs completed {}", ???);
} }
} }

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@ -1,5 +1,7 @@
// threads3.rs // threads3.rs
// Execute `rustlings hint threads3` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint threads3` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,13 +1,11 @@
// traits1.rs // traits1.rs
// Time to implement some traits!
// //
// Your task is to implement the trait // Time to implement some traits! Your task is to implement the trait
// `AppendBar` for the type `String`. // `AppendBar` for the type `String`. The trait AppendBar has only one function,
// which appends "Bar" to any object implementing this trait.
// //
// The trait AppendBar has only one function, // Execute `rustlings hint traits1` or use the `hint` watch subcommand for a
// which appends "Bar" to any object // hint.
// implementing this trait.
// Execute `rustlings hint traits1` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,14 +1,11 @@
// traits2.rs // traits2.rs
// //
// Your task is to implement the trait // Your task is to implement the trait `AppendBar` for a vector of strings. To
// `AppendBar` for a vector of strings. // implement this trait, consider for a moment what it means to 'append "Bar"'
//
// To implement this trait, consider for
// a moment what it means to 'append "Bar"'
// to a vector of strings. // to a vector of strings.
// //
// No boiler plate code this time, // No boiler plate code this time, you can do this!
// you can do this! //
// Execute `rustlings hint traits2` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint traits2` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,11 +1,12 @@
// traits3.rs // traits3.rs
// //
// Your task is to implement the Licensed trait for // Your task is to implement the Licensed trait for both structures and have
// both structures and have them return the same // them return the same information without writing the same function twice.
// information without writing the same function twice.
// //
// Consider what you can add to the Licensed trait. // Consider what you can add to the Licensed trait.
// Execute `rustlings hint traits3` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint traits3` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,8 +1,11 @@
// traits4.rs // traits4.rs
// //
// Your task is to replace the '??' sections so the code compiles. // Your task is to replace the '??' sections so the code compiles.
//
// Don't change any line other than the marked one. // Don't change any line other than the marked one.
// Execute `rustlings hint traits4` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint traits4` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,8 +1,11 @@
// traits5.rs // traits5.rs
// //
// Your task is to replace the '??' sections so the code compiles. // Your task is to replace the '??' sections so the code compiles.
//
// Don't change any line other than the marked one. // Don't change any line other than the marked one.
// Execute `rustlings hint traits5` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint traits5` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,6 +1,9 @@
// variables1.rs // variables1.rs
//
// Make me compile! // Make me compile!
// Execute `rustlings hint variables1` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint variables1` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,5 +1,7 @@
// variables2.rs // variables2.rs
// Execute `rustlings hint variables2` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint variables2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,5 +1,7 @@
// variables3.rs // variables3.rs
// Execute `rustlings hint variables3` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint variables3` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,5 +1,7 @@
// variables4.rs // variables4.rs
// Execute `rustlings hint variables4` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint variables4` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,5 +1,7 @@
// variables5.rs // variables5.rs
// Execute `rustlings hint variables5` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint variables5` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,5 +1,7 @@
// variables6.rs // variables6.rs
// Execute `rustlings hint variables6` or use the `hint` watch subcommand for a hint. //
// Execute `rustlings hint variables6` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,7 +1,10 @@
// vecs1.rs // vecs1.rs
// Your task is to create a `Vec` which holds the exact same elements //
// as in the array `a`. // Your task is to create a `Vec` which holds the exact same elements as in the
// array `a`.
//
// Make me compile and pass the test! // Make me compile and pass the test!
//
// Execute `rustlings hint vecs1` or use the `hint` watch subcommand for a hint. // Execute `rustlings hint vecs1` or use the `hint` watch subcommand for a hint.
// I AM NOT DONE // I AM NOT DONE

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@ -1,6 +1,7 @@
// vecs2.rs // vecs2.rs
// A Vec of even numbers is given. Your task is to complete the loop //
// so that each number in the Vec is multiplied by 2. // A Vec of even numbers is given. Your task is to complete the loop so that
// each number in the Vec is multiplied by 2.
// //
// Make me pass the test! // Make me pass the test!
// //