1. Set or Clear a Specific Bit in a Register

#include <stdio.h>
unsigned char modifyBit(unsigned char reg, int pos, int mode) 
{
   if(mode == 1)
    {
        reg |= (1 << pos); //0000 0100 -> 0000 0101 |= 0000 0100 -> 0000 0101
    }
    else
    {
        reg &= ~(1 << pos); 
    }
    return reg;
}

int main() {
   unsigned char reg;
   int pos, mode;
   scanf("%hhu %d %d", &reg, &pos, &mode);
   printf("%d", modifyBit(reg, pos, mode));
   return 0;
}