Bit operators / | - bitwise OR / Essential C++

#include <iostream>
#include <string>

int main(int argc, char **argv) {
    int a = 5;  // 0101b  (0x05)
    a |= 12;    // a = 0101b | 1101b == 13

    std::cout << "a = " << a << std::endl;
}