1. Set or Clear a Specific Bit in a Register

#include <stdio.h>

int main()
{
    unsigned char reg;
    int pos, mode;

    scanf("%hhu %d %d", &reg, &pos, &mode);

    if(mode == 1)
        reg = reg | (1 << pos);
    else
        reg = reg & ~(1 << pos);

    printf("%d", reg);

    return 0;
}