비트 연산

unsigned int flags = 0;
flags |= 1u << 2;
flags &= ~(1u << 1);
if (flags & (1u << 2)) {
    /* bit 2 is on */
}

#include <stdio.h>

enum {
    READ_FLAG = 1u << 0,
    WRITE_FLAG = 1u << 1,
    EXEC_FLAG = 1u << 2
};

int main(void) {
    unsigned int permission = READ_FLAG | WRITE_FLAG;

    if (permission & WRITE_FLAG) {
        printf("write enabled\n");
    }

    permission ^= READ_FLAG;
    printf("permission = %u\n", permission);
    return 0;
}