#include <iostream>
#include <cstdio>

unsigned bit_zero(unsigned x, int p, int n){
    const int l = (sizeof(x) << 3) - (p + n);
    unsigned  y = ~0;
    return x & ~((((y << l) >> l) >> p) << p);
}

int main(void){
    unsigned x = 0xFFFFFFFFU;
    printf("%08X\n", bit_zero(x, 0,  4));
    printf("%08X\n", bit_zero(x, 8,  16));
    printf("%08X\n", bit_zero(x, 16, 8));
    return 0;
}