c - 如何将长无符号转换为无符号char *？

Question

我正在尝试哈希unsigned long值，但是哈希函数采用unsigned char *，如以下实现所示:

unsigned long djb2(unsigned char *key, int n)
{
    unsigned long hash = 5381;
    int i = 0;
    while (i < n-8) {
        hash = hash * 33 + key[i++];
        hash = hash * 33 + key[i++];
        hash = hash * 33 + key[i++];
        hash = hash * 33 + key[i++];
        hash = hash * 33 + key[i++];
        hash = hash * 33 + key[i++];
        hash = hash * 33 + key[i++];
        hash = hash * 33 + key[i++];
    }
    while (i < n)
        hash = hash * 33 + key[i++];
    return hash;
}

有没有办法实现我的目标，也许在两者之间进行转换？

Answer 1

unsigned long x;

unsigned char * p = (unsigned char*)&x;

确保通过p使用所有4个字节，或者系统上unsigned long的长度是多少。