Fix the 'lifetime may not live long enough' error by adding explicit lifetime parameters to function signatures to ensure returned references remain valid.
Add an explicit lifetime parameter to your function signature to tell the compiler how long the returned reference is valid.
fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
if x.len() > y.len() { x } else { y }
}
This ensures the returned reference lives as long as the shortest of the two input references.
The "lifetime may not live long enough" error happens when you try to return a reference to data that might disappear before you use it. Think of it like lending a book: you can't promise to return the book to the library if you don't know when the library will close. Adding a lifetime tells the compiler exactly how long your borrowed data will stay valid, preventing crashes from accessing deleted memory.