mirror of
https://github.com/rust-lang/rustlings.git
synced 2026-01-12 13:49:19 +00:00
27 lines
821 B
Rust
27 lines
821 B
Rust
// lifetimes2.rs
|
||
//
|
||
// So if the compiler is just validating the references passed
|
||
// to the annotated parameters and the return type, what do
|
||
// we need to change?
|
||
//
|
||
// Execute `rustlings hint lifetimes2` or use the `hint` watch subcommand for a hint.
|
||
|
||
fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
|
||
if x.len() > y.len() {
|
||
x
|
||
} else {
|
||
y
|
||
}
|
||
}
|
||
|
||
fn main() {
|
||
let string1 = String::from("long string is long"); //'a
|
||
{
|
||
//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：
|
||
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
|
||
let string2 = String::from("xyz"); //'b
|
||
result = longest(string1.as_str(), string2.as_str());
|
||
println!("The longest string is '{}'", result);
|
||
}
|
||
}
|