trpl-zh-cn/listings/ch09-error-handling/listing-09-11/src/main.rs

16 lines
367 B
Rust

// ANCHOR: here
fn last_char_of_first_line(text: &str) -> Option<char> {
text.lines().next()?.chars().last()
}
// ANCHOR_END: here
fn main() {
assert_eq!(
last_char_of_first_line("Hello, world\nHow are you today?"),
Some('d')
);
assert_eq!(last_char_of_first_line(""), None);
assert_eq!(last_char_of_first_line("\nhi"), None);
}