17. Extract the Nibble from an 8-bit Register

#include <stdio.h>

unsigned char extractNibble(unsigned char reg, int pos) {
    if(reg !=0 && (pos == 0 || pos == 1))
    {
        if(pos == 0)
            reg = reg & 0x0F;
        else if(pos == 1)
            reg = (reg >> 4) & 0x0F;

        return reg;
    }
    else
        return 0;
}

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