20. Clear Specific Bits in a 32-bit Register

#include <stdio.h>
#include <stdint.h>

int main() {
    uint32_t reg;
    int pos, len;

    scanf("%u", &reg);   // 32-bit register
    scanf("%d", &pos);   // starting bit position
    scanf("%d", &len);   // number of bits to clear

    reg = reg & ~(((1U << len) - 1) << pos);

    printf("%u", reg);
    return 0;
}