如何在c中编写替换函数

Question

编写一个函数，该函数将返回i x个b字节已替换为unsigned replace_f (unsigned x, int i, unsigned char b){ } 的值：

replace_f(0x12345678, 2, 0xBC) --> 0x12BC5678

EX：{{1}}

Answer 1

没试过，但这可行：

unsigned replace_f (unsigned x, int i, unsigned char b){
    char *c;

    c = (char *)&x;
    c[i] = b;
    return x;
}

Answer 2

unsigned replace_f (unsigned x, int i, unsigned char b){
    unsigned char *place = (unsigned char*)&x;
    place[sizeof(int)-i] = b;
    return x;
}

假设小端