练习 2-6 编写一个函数 setbits(x, p, n, y)，该函数返回对x执行下列操作后的结果值：将x中从第p位开始的n个（二进制）位设置为y中最右边n位的值，x的其余各位保持不变。

#include<stdio.h>
#include <stdlib.h>

int setbits(int x, int p, int n, int y);
void TenToTwo(int);//将十进制数换成二进制数示出

int main() {
    int x, p, n, y;
    printf("setbits(x, p, n, y)");
    printf("please input x");
    scanf("%d",&x);
    printf("please input p");
    scanf("%d", &p);
    printf("please input n");
    scanf("%d", &n);
    printf("please input y");
    scanf("%d", &y);

    printf("outputs x and y in binary form, respectively\nx:");
    TenToTwo(x);
    printf("\ny:");
    TenToTwo(y);

    int ss;
    ss=setbits(x, p, n, y);
    printf("setbits(x, p, n, y)\nx:");
    TenToTwo(ss);

    system("pause");
}
void TenToTwo(int ten) {
    int two[100];
    int shang = ten;
    int yu;
    int i = 0;
    while (shang != 0) {
        yu = shang % 2;
        shang = shang / 2;
        two[i++] = yu;
    }
    for (int j = i - 1; j >= 0; --j) {
        printf("%d", two[j]);
    }
    printf("\n");
}

int setbits(int x, int p, int n, int y) {
    return x &~(~(~0 << n) << (p - n)) | (y & ~(~0 << n)) << (p - n);
}