#include <stdio.h>

/* returns 1 if the bit in value is set, and 0 otherwise */

int test_bit(unsigned int value, int bit_number) {
    unsigned 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) {
    unsigned 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) {
    unsigned int mask = ~(1 << bit_number);
    *value = *value & mask; 
}


int main() {
    unsigned int value;
    int i;

    /* test testing a bit */
    printf("Enter a number: ");
    scanf("%d", &value);

    for (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);

    return 0;
}