17. Extract the Nibble from an 8-bit Register

#include <stdio.h>

unsigned char extractNibble(unsigned char reg, int pos) {
   int x = reg&~(1<<0)&~(1<<1)&~(1<<2)&~(1<<3);
   int y = reg - x;
   if(pos == 1){
    reg  = x/16;
   }else if(pos == 0){
    reg = y;
   }
    return reg;
}

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