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// In this exercise, you'll learn some of the unique advantages that iterators
// can offer.
// TODO: Complete the `capitalize_first` function.
// "hello" -> "Hello"
fn capitalize_first(input: &str) -> String {
let mut chars = input.chars();
match chars.next() {
None => String::new(),
Some(first) => first.to_uppercase().to_string() + &input[1..],
}
}
// TODO: Apply the `capitalize_first` function to a slice of string slices.
// Return a vector of strings.
// ["hello", "world"] -> ["Hello", "World"]
fn capitalize_words_vector(words: &[&str]) -> Vec<String> {
let mut v = Vec::new();
for word in words {
if !word.trim().is_empty() {
v.push(capitalize_first(word));
}
}
v
}
// TODO: Apply the `capitalize_first` function again to a slice of string
// slices. Return a single string.
// ["hello", " ", "world"] -> "Hello World"
fn capitalize_words_string(words: &[&str]) -> String {
capitalize_words_vector(words).join(" ")
}
fn main() {
// You can optionally experiment here.
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_success() {
assert_eq!(capitalize_first("hello"), "Hello");
}
#[test]
fn test_empty() {
assert_eq!(capitalize_first(""), "");
}
#[test]
fn test_iterate_string_vec() {
let words = vec!["hello", "world"];
assert_eq!(capitalize_words_vector(&words), ["Hello", "World"]);
}
#[test]
fn test_iterate_into_string() {
let words = vec!["hello", " ", "world"];
assert_eq!(capitalize_words_string(&words), "Hello World");
}
}
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