1. Set or Clear a Specific Bit in a Register

#include <stdio.h>

unsigned char modifyBit(unsigned char reg, int pos, int mode) {
    if ((pos > 7) || (pos < 0))
        return reg;
        
    switch(mode){
    case 0:
        return (reg & (~(1 << pos)));
        break;
    case 1:
        return (reg | (1 << pos));
        break;
    default:
        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;
}