Example
// The Option type can either contain Some value or None.
fn find(value: i32, slice: &[i32]) -> Option<usize> {
for (index, &element) in slice.iter().enumerate() {
if element == value {
// Return a value (wrapped in Some).
return Some(index);
}
}
// Return no value.
None
}
fn main() {
let array = [1, 2, 3, 4, 5];
// Pattern match against the Option value.
if let Some(index) = find(2, &array) {
// Here, there is a value.
println!("The element 2 is at index {}.", index);
}
// Check if the result is None (no value).
if let None = find(12, &array) {
// Here, there is no value.
println!("The element 12 is not in the array.");
}
// You can also use `is_some` and `is_none` helpers
if find(12, &array).is_none() {
println!("The element 12 is not in the array.");
}
}
