1. Set or Clear a Specific Bit in a Register

#include <stdio.h>

unsigned char modifyBit(unsigned char reg, int pos, int mode) {
    // mode == 1 → set bit, mode == 0 → clear bit
    if (mode == 1) {
        reg |= (1u << pos);      // set bit at pos
    } else {
        reg &= ~(1u << pos);     // clear bit at 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;
}