67 lines
1.7 KiB
Rust
67 lines
1.7 KiB
Rust
// iterators2.rs
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//
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// In this exercise, you'll learn some of the unique advantages that iterators
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// can offer. Follow the steps to complete the exercise.
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//
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// Execute `rustlings hint iterators2` or use the `hint` watch subcommand for a
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// hint.
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// Step 1.
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// Complete the `capitalize_first` function.
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// "hello" -> "Hello"
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pub fn capitalize_first(input: &str) -> String {
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let mut c = input.chars();
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match c.next() {
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None => String::new(),
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Some(first) => {
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first.to_ascii_uppercase().to_string() + c.as_str()
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},
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}
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}
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// Step 2.
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// Apply the `capitalize_first` function to a slice of string slices.
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// Return a vector of strings.
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// ["hello", "world"] -> ["Hello", "World"]
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pub fn capitalize_words_vector(words: &[&str]) -> Vec<String> {
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words.iter().map(|x| capitalize_first(x)).collect()
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}
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// Step 3.
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// Apply the `capitalize_first` function again to a slice of string slices.
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// Return a single string.
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// ["hello", " ", "world"] -> "Hello World"
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pub fn capitalize_words_string(words: &[&str]) -> String {
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let one_string: String = words.iter().map(|x| capitalize_first(x)).collect();
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one_string
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_success() {
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assert_eq!(capitalize_first("hello"), "Hello");
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}
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#[test]
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fn test_empty() {
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assert_eq!(capitalize_first(""), "");
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}
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#[test]
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fn test_iterate_string_vec() {
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let words = vec!["hello", "world"];
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assert_eq!(capitalize_words_vector(&words), ["Hello", "World"]);
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}
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#[test]
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fn test_iterate_into_string() {
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let words = vec!["hello", " ", "world"];
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assert_eq!(capitalize_words_string(&words), "Hello World");
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}
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}
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