1. Set or Clear a Specific Bit in a Register

#include <stdio.h>

int main() {
    unsigned char reg;
    int pos, mode;

    scanf("%hhu %d %d",&reg,&pos,&mode);

    if(reg > 255 || pos < 0 || pos > 7 || (mode != 0 && mode != 1)) {
        printf("Invalid input");
        return 0;
    }

    if(mode == 1) {
        reg |= (1 << pos);
    } else {
        reg &= ~(1 << pos);
    }

    printf("%u", reg);
    return 0;
}