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2cdd61294f
The `watch` command now requires user action to move to the next exercise. BREAKING CHANGE: this changes the behavior of `watch`.
148 lines
2.1 KiB
Rust
148 lines
2.1 KiB
Rust
// iterators2.rs
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// In this module, you'll learn some of unique advantages that iterators can offer
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// Step 1. Complete the `capitalize_first` function to pass the first two cases
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// Step 2. Apply the `capitalize_first` function to a vector of strings, ensuring that it returns a vector of strings as well
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// Step 3. Apply the `capitalize_first` function again to a list, but try and ensure it returns a single string
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// As always, there are hints below!
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// I AM NOT DONE
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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) => first.collect::<String>() + c.as_str(),
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}
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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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// Step 1.
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// Tests that verify your `capitalize_first` function implementation
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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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// Step 2.
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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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let capitalized_words: Vec<String> = // TODO
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assert_eq!(capitalized_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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let capitalized_words = // TODO
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assert_eq!(capitalized_words, "Hello World");
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}
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}
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// Step 1
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// You need to call something on `first` before it can be collected
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// Currently its type is `char`. Have a look at the methods that are available on that type:
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// https://doc.rust-lang.org/std/primitive.char.html
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// Step 2
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// First you'll need to turn the Vec into an iterator
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// Then you'll need to apply your function unto each item in the vector
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// P.s. Don't forget to collect() at the end!
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// Step 3.
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// This is very similar to the previous test. The only real change is that you will need to
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// alter the type that collect is coerced into. For a bonus you could try doing this with a
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// turbofish
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