1. Set or Clear a Specific Bit in a Register

#include <stdio.h>

unsigned char modifyBit(unsigned char reg, int pos, int mode) {
  
    // Write your code here
    unsigned char *ptr;
    ptr = &reg;
    unsigned char mark = 0;
    if (mode == 0){
        
        mark = 1 << pos;
        mark = ~mark;
         *ptr = (*ptr) & mark ;
        }
    
    if (mode == 1){
        mark = 1 << pos;
       *ptr = (*ptr) | mark ; 
    };

    return *ptr; 
}

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