1. Set or Clear a Specific Bit in a Register

#include <stdio.h>

unsigned char modBit(unsigned char reg, int pos, int mode) {
    if (mode == 1) {
        reg |= (1 << pos);
    }
    else {
        reg &= ~(1 << pos);
    }
    return reg;
}

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