(녹 롱) 40번째 옵션
// Option<T> fn take_fifth(value: Vec<i32>) -> Option<i32> { if value.len() < 5 { None } else { Some(value(4)) // i32 } } fn main() { let new_vec = vec!(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10); let index = take_fifth(new_vec); println!(“{:?}”, index); } // Option<T> fn take_fifth(value: Vec<i32>) -> Option<i32> { if … Read more