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To understand From-based conversion, an understanding of traits is required, which we teach in a later chapter. The From trait specifically is taught in one of the conversion exercises. So, we can safely remove it here without users missing out on learning something important. A specific source of confusion for users was a warning that the conversion is useless, which appeared when using the `string_slice` function for the expression with `.into()`. closes #2190
36 lines
983 B
Rust
36 lines
983 B
Rust
// Calls of this function should be replaced with calls of `string_slice` or `string`.
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fn placeholder() {}
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fn string_slice(arg: &str) {
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println!("{arg}");
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}
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fn string(arg: String) {
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println!("{arg}");
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}
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// TODO: Here are a bunch of values - some are `String`, some are `&str`.
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// Your task is to replace `placeholder(…)` with either `string_slice(…)`
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// or `string(…)` depending on what you think each value is.
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fn main() {
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placeholder("blue");
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placeholder("red".to_string());
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placeholder(String::from("hi"));
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placeholder("rust is fun!".to_owned());
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placeholder(format!("Interpolation {}", "Station"));
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// WARNING: This is byte indexing, not character indexing.
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// Character indexing can be done using `s.chars().nth(INDEX)`.
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placeholder(&String::from("abc")[0..1]);
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placeholder(" hello there ".trim());
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placeholder("Happy Monday!".replace("Mon", "Tues"));
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placeholder("mY sHiFt KeY iS sTiCkY".to_lowercase());
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}
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