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27 lines
821 B
Rust
27 lines
821 B
Rust
// lifetimes2.rs
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//
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// So if the compiler is just validating the references passed
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// to the annotated parameters and the return type, what do
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// we need to change?
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//
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// Execute `rustlings hint lifetimes2` or use the `hint` watch subcommand for a hint.
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fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
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if x.len() > y.len() {
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x
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} else {
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y
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}
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}
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fn main() {
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let string1 = String::from("long string is long"); //'a
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{
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//这意味着返回值的生命周期与参数生命周期中的较小值一致：
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let result; //返回值引用的生命周期，应该小于等于x，y 里面最短的那个
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let string2 = String::from("xyz"); //'b
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result = longest(string1.as_str(), string2.as_str());
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println!("The longest string is '{}'", result);
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}
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}
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