1. Set or Clear a Specific Bit in a Register

#include <stdio.h>

unsigned char modifyBit(unsigned char reg, int pos, int mode) {
    unsigned char modified = (mode == 1) 
        ? (reg | (1u << pos))  & 0xff // set
        : (reg & ~(1u << pos)) & 0xff // clear
        ;
    return modified;
}

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