#include <stdio.h>
#include <limits.h>

/* First we need a bit field */
#define BIT_1           (1<<0)    // 2^0, bit 1
#define BIT_2           (1<<1)    // 2^1, bit 2
#define BIT_3           (1<<2)    // 2^2, bit 3
#define BIT_4           (1<<3)    // 2^3, bit 4
#define BIT_5           (1<<4)    // 2^4, bit 5
#define BIT_6           (1<<5)    // 2^5, bit 6
#define BIT_7           (1<<6)    // 2^6, bit 7
#define BIT_8           (1<<7)    // 2^7, bit 8

/* All bits set: 128+64+32+16+8+4+2+1 = 255 = 0xFF */
int main() {

    char bits = 0;

    bits |= BIT_1;  // set bit 1
    bits |= BIT_4;  // set bit 4
    bits &= ~BIT_4; // unset bit 4 again
    bits ^= BIT_5;  // flip bit 5

    // check which bits are set
    for(int i=0; i<CHAR_BIT; i++)
        printf("Bit %d is: %s\n", i + 1, (bits & (1<<i)) ? "on" : "off");

    printf("This char has %d bits.\n", CHAR_BIT);

    return 0;
}