How do I convert a boolean to an integer in Rust?

Question

How do I convert a boolean to an integer in Rust? As in, true becomes 1, and false becomes 0.

Answer 1

A boolean value in Rust is guaranteed to be 1 or 0:

The bool represents a value, which could only be either true or false. If you cast a bool into an integer, true will be 1 and false will be 0.

A boolean value, which is neither 0 nor 1 is undefined behavior:

A value other than false (0) or true (1) in a bool.

Therefore, you can just cast it to a primitive:

assert_eq!(0, false as i32);
assert_eq!(1, true as i32);

Answer 2

You may use .into():

let a = true;
let b: i32 = a.into();
println!("{}", b); // 1

let z: isize = false.into();
println!("{}", z); // 0

playground

Answer 3

Use an if statement:

if some_boolean { 1 } else { 0 }

See also:

• How can I port C++ code that uses the ternary operator to Rust?

Answer 4

Cast it:

fn main() {
    println!("{}", true as i32)
}