Split string only once in Rust

You are looking for str::splitn:

fn split_once(in_string: &str) -> (&str, &str) { let mut splitter = in_string.splitn(2, ':'); let first = splitter.next().unwrap(); let second = splitter.next().unwrap(); (first, second) } fn main() { let (a, b) = split_once("hello:world:earth"); println!("{} --- {}", a, b) } 

Note that Rust uses snake_case.

I guess it's saying that because splitter only exists inside the function block

Nope, it's because you've created a String and are trying to return a reference to it; you cannot do that. second is what doesn't live long enough.

How to I coerce second into existing beyond the function block?

You don't. This is a fundamental aspect of Rust. If something needs to live for a certain mount of time, you just have to make it exist for that long. In this case, as in the linked question, you'd return the String:

fn split_once(in_string: &str) -> (&str, String) { let mut splitter = in_string.split(':'); let first = splitter.next().unwrap(); let second = splitter.fold("".to_string(), |a, b| a + b); (first, second) }