#include <stdio.h>

/* return whether a given bit is 1 or not */
int test_bit(unsigned int value, int bit_number) {
    int mask = 1 << bit_number;

    if ((value & mask) == 0) {
        return 0;
    } else {
        return 1;
    }
}

/* sets a bit in a number to 1 */
void set_bit(unsigned int* value, int bit_number) {
    int mask = 1 << bit_number;

    *value = *value | mask;
}

/* clear a bit in a number to 0 */
void clear_bit(unsigned int* value, int bit_number) {
    int mask = ~(1 << bit_number);

    *value = *value & mask;
}

/* invert a given bit in a number */
void flip_bit(unsigned int* value, int bit_number) {
    int mask = 1 << bit_number;

    *value = *value ^ mask;
}

int main() {
    unsigned int value;

    /* test testing a bit */
    printf("Enter a number: ");
    scanf("%d", &value);
    for (int i = 31; i >= 0; i--) {
        printf("%d", test_bit(value, i));
    }
    printf("\n");

    /* test setting a bit. should print 21 */
    value = 0;
    set_bit(&value, 0);
    set_bit(&value, 2);
    set_bit(&value, 4);
    printf("%d (should say 21)\n", value);

    /* test clearing a bit, should print 42 */
    value = 63;
    clear_bit(&value, 0);
    clear_bit(&value, 2);
    clear_bit(&value, 4);
    printf("%d (should say 42)\n", value);

    /* test swapping a bit, should print 57 */
    value = 53;
    flip_bit(&value, 3);
    flip_bit(&value, 2);
    printf("%d (should say 57)\n", value);

    return 0;
}