diff options
| -rw-r--r-- | exercises/14_generics/generics1.rs | 19 | ||||
| -rw-r--r-- | rustlings-macros/info.toml | 7 | ||||
| -rw-r--r-- | solutions/14_generics/generics1.rs | 18 |
3 files changed, 38 insertions, 6 deletions
diff --git a/exercises/14_generics/generics1.rs b/exercises/14_generics/generics1.rs index c023e64..87ed990 100644 --- a/exercises/14_generics/generics1.rs +++ b/exercises/14_generics/generics1.rs @@ -1,7 +1,18 @@ -// This shopping list program isn't compiling! Use your knowledge of generics to -// fix it. +// `Vec<T>` is generic over the type `T`. In most cases, the compiler is able to +// infer `T`, for example after pushing a value with a concrete type to the vector. +// But in this exercise, the compiler needs some help through a type annotation. fn main() { - let mut shopping_list: Vec<?> = Vec::new(); - shopping_list.push("milk"); + // TODO: Fix the compiler error by annotating the type of the vector + // `Vec<T>`. Choose `T` as some integer type that can be created from + // `u8` and `i8`. + let mut numbers = Vec::new(); + + // Don't change the lines below. + let n1: u8 = 42; + numbers.push(n1.into()); + let n2: i8 = -1; + numbers.push(n2.into()); + + println!("{numbers:?}"); } diff --git a/rustlings-macros/info.toml b/rustlings-macros/info.toml index dc288c0..23eb304 100644 --- a/rustlings-macros/info.toml +++ b/rustlings-macros/info.toml @@ -734,8 +734,13 @@ test = false hint = """ Vectors in Rust make use of generics to create dynamically sized arrays of any type. +If the vector `numbers` has the type `Vec<T>`, then we can only push values of +type `T` to it. By using `into()` before pushing, we ask the compiler to convert +`n1` and `n2` to `T`. But the compiler doesn't know what `T` is yet and needs a +type annotation. -You need to tell the compiler what type we are pushing onto this vector.""" +`u8` and `i8` can both be converted to `i16`, `i32` and `i64`. Choose one for +the generic of the vector.""" [[exercises]] name = "generics2" diff --git a/solutions/14_generics/generics1.rs b/solutions/14_generics/generics1.rs index 4e18198..e2195fd 100644 --- a/solutions/14_generics/generics1.rs +++ b/solutions/14_generics/generics1.rs @@ -1 +1,17 @@ -// Solutions will be available before the stable release. Thank you for testing the beta version 🥰 +// `Vec<T>` is generic over the type `T`. In most cases, the compiler is able to +// infer `T`, for example after pushing a value with a concrete type to the vector. +// But in this exercise, the compiler needs some help through a type annotation. + +fn main() { + // `u8` and `i8` can both be converted to `i16`. + let mut numbers: Vec<i16> = Vec::new(); + // ^^^^^^^^^^ added + + // Don't change the lines below. + let n1: u8 = 42; + numbers.push(n1.into()); + let n2: i8 = -1; + numbers.push(n2.into()); + + println!("{numbers:?}"); +} |
