17. Extract the Nibble from an 8-bit Register

#include <stdio.h>

unsigned char extractNibble(unsigned char reg, int pos) {
    // Write your code here
    if(pos == 1)
    {
        //extract upper nibble
        reg >>= 4;
        // make sure the upper is zero
        reg &=0x0f;  
    }
    else if( pos ==0)
    {
        reg &= 0x0f; 

    }
    else{
        printf("Invalid pos");
        reg = 0;
    }
    return reg;
}

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