17. Extract the Nibble from an 8-bit Register

#include <stdio.h>

unsigned char extractNibble(unsigned char reg, int pos)
{
    if(pos==0)
    {
        return reg=reg&0x0f;
    }
    else if(pos==1)
    {
        return reg=(reg>>4)&0x0f;
    }
}

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