17. Extract the Nibble from an 8-bit Register

#include <stdio.h>

unsigned char extractNibble(unsigned char reg, int pos) {
    if (pos == 0) {
        // Lower nibble
        return reg & 0x0F;
    } else if (pos == 1) {
        // Upper nibble
        return (reg >> 4) & 0x0F;
    }
    return 0; // invalid pos
}

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