Get number of set bits in a decimal number

number_of_set_bits_for_a_number.rs

use std::io;

fn number_of_bits(num: u32) -> u32 {
    let mut count = 0;
    let mut copy_num = num;
    while copy_num > 0 {
        count += 1;
        copy_num = copy_num & (copy_num - 1);
    }
    count
}

fn read_input() -> String {
    let mut text = String::new();
    io::stdin().read_line(&mut text).unwrap();
    text
}

fn read_integer() -> u64 {
    let input = read_input();
    let integer: u64 = input.trim().parse().unwrap();
    integer
}

fn main() {
    println!("Enter number of test cases: ");
    let cases = read_integer();
    let mut test_cases: u32 = cases as u32;
    println!("Enter input for test case: ");
    while test_cases > 0 {
        let num: u32 = read_integer() as u32;
        let no_of_bits = number_of_bits(num);
        println!("Result: {}", no_of_bits);

        test_cases -= 1;
    }
}