1. Set or Clear a Specific Bit in a Register

#include <stdio.h>

// 0 << 3; 1 <<3; === 0000; 1000;

// 1010 - > 0010; 
// 

unsigned char modifyBit(unsigned char reg, int pos, int mode) {
    reg = mode ? reg | (mode << pos) : 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;
}