Unit Type

The () type, also called “unit”. The () type has exactly one value () , and is used when there is no other meaningful value that could be returned.

The empty tuple type, () , is called “unit”, and serves as Rust's void type (unlike void , () has exactly one value, also named () , which is zero-sized).

Example 1

fn main() {
    let my_tuple = (42, "hello", ());
    println!("Tuple: {:?}", my_tuple);
}

In this example, the tuple my_tuple contains an integer, a string, and a unit type (). When you run the code, it will print:

Tuple: (42, "hello", ())

Example 2

fn main() {
    let result = do_nothing();
    println!("Result of do_nothing: {:?}", result);
}

fn do_nothing() -> () {
    // This function does nothing and returns unit type
}