Count the number of leading and trailing zeroes in an integer.

num_zeros.cpp

/**
 *  Count the number of leading and trailing zeroes in an integer
 *
 *  g++ -std=c++11 -Wall -Wextra -Werror -pedantic-errors num_zeros.cpp -o num_zeros
 */

#include <iostream>
#include <cstdint>



template <typename int_t>
constexpr int_t num_trailing_zeros(int_t i, unsigned numZeros = 0) {
    return !i ? numZeros : num_trailing_zeros(i >> 1, numZeros+1);
}



template <typename int_t>
constexpr int_t num_leading_zeros(int_t i) {
    return (sizeof(int_t) * CHAR_BIT) - num_trailing_zeros(i);
}



int main() {
    std::cout << num_leading_zeros(1) << std::endl;
    std::cout << num_leading_zeros(2) << std::endl;
    std::cout << num_leading_zeros(3) << std::endl;
    
    return 0;
}