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 == 0 ) { //Clear
        unsigned char mask = ~(1 << pos);
        return reg &= mask;
    } else {            // Set
        unsigned char mask = (1 << pos);
        return reg |= mask;
    }
    return 0;
}

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