1. Set or Clear a Specific Bit in a Register

#include <stdio.h>

unsigned char modifyBit(unsigned char reg, int pos, int mode) {

    unsigned char myBit[8] = {0};


    for(int i = 0; i <8; ++i)
    {
        if(i == pos)
        {
            if(mode == 1)
            {
                myBit[i] = 1;
            }
            else
            {
                myBit[i] = 0;
            }
        }
        else
        {
            myBit[i] = (reg & 1);
        }
        reg >>= 1;
    }

    unsigned int exp = 1;
    unsigned int num = 0;

    for(int i = 0; i < 8; ++i)
    {
         num = num + myBit[i] * exp;
         exp <<= 1;
    }
    return num;
}

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