如何编写C

Question

一个替代函数编写将返回在其中xi个字节已经取代b值的函数：

unsigned replace_f (unsigned x, int i, unsigned char b){ 

} 

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

Answer 1

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

ASSU我小endian

Answer 2

没有尝试一下，不过这可能是工作：

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

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