Lifetimes

Lifetimes\n\nLifetimes ensure that references are valid for as long as they are used.\n\nrust\nfn longest<'a>(a: &'a str, b: &'a str) -> &'a str {\n if a.len() > b.len() { a } else { b }\n}\n\nfn main() {\n let s1 = \"short\";\n let s2 = \"much longer string\";\n let result = longest(s1, s2);\n println!(\"Longest: {}\", result);\n}\n\n