146 lines
2.1 KiB
Rust
146 lines
2.1 KiB
Rust
// iterators2.rs
|
|
// In this module, you'll learn some of unique advantages that iterators can offer
|
|
// Step 1. Complete the `capitalize_first` function to pass the first two cases
|
|
// Step 2. Apply the `capitalize_first` function to a vector of strings, ensuring that it returns a vector of strings as well
|
|
// Step 3. Apply the `capitalize_first` function again to a list, but try and ensure it returns a single string
|
|
// As always, there are hints below!
|
|
|
|
pub fn capitalize_first(input: &str) -> String {
|
|
let mut c = input.chars();
|
|
match c.next() {
|
|
None => String::new(),
|
|
Some(first) => first.collect::<String>() + c.as_str(),
|
|
}
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use super::*;
|
|
|
|
// Step 1.
|
|
// Tests that verify your `capitalize_first` function implementation
|
|
#[test]
|
|
fn test_success() {
|
|
assert_eq!(capitalize_first("hello"), "Hello");
|
|
}
|
|
|
|
#[test]
|
|
fn test_empty() {
|
|
assert_eq!(capitalize_first(""), "");
|
|
}
|
|
|
|
// Step 2.
|
|
#[test]
|
|
fn test_iterate_string_vec() {
|
|
let words = vec!["hello", "world"];
|
|
let capitalized_words: Vec<String> = // TODO
|
|
assert_eq!(capitalized_words, ["Hello", "World"]);
|
|
}
|
|
|
|
#[test]
|
|
fn test_iterate_into_string() {
|
|
let words = vec!["hello", " ", "world"];
|
|
let capitalized_words = // TODO
|
|
assert_eq!(capitalized_words, "Hello World");
|
|
}
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
// Step 1
|
|
// You need to call something on `first` before it can be collected
|
|
// Currently its type is `char`. Have a look at the methods that are available on that type:
|
|
// https://doc.rust-lang.org/std/primitive.char.html
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
// Step 2
|
|
// First you'll need to turn the Vec into an iterator
|
|
// Then you'll need to apply your function unto each item in the vector
|
|
// P.s. Don't forget to collect() at the end!
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
// Step 3.
|
|
// This is very similar to the previous test. The only real change is that you will need to
|
|
// alter the type that collect is coerced into. For a bonus you could try doing this with a
|
|
// turbofish
|