在做HMAC編碼時發現一個詭異的問題，結果是由於C 字串陣列和char*指標在做&操作時的區別導致的，HMAC編碼時發現的問題見這裡。本文介紹C 字串陣列和char*指標在做&操作時的區別。

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <iostream>
using namespace std;

int main(int argc, char * argv[]) {
        char buff[] = "hello";
        printf("buff: %p\n", buff);
        printf("&buff: %p\n", &buff);
        for(int i = 0; i < strlen(buff) + 1; ++i) {
                printf("%-03x", (unsigned int)buff[i]);
        }
        cout << endl;

        char * pBuff = (char *)malloc(strlen("hello") + 1);
        memset(pBuff, 0, strlen("hello") + 1);
        strcpy(pBuff, "hello");
        cout << "pBuff: " << pBuff << "~" << endl;

        printf("pBuff: %p\n", pBuff);
        printf("&pBuff: %p\n", &pBuff);

        free(pBuff);

        return 0;
}
 

buff: 0x7fffde8fe990
&buff: 0x7fffde8fe990
68 65 6c 6c 6f 0
pBuff: hello~
pBuff: 0x7ef010
&pBuff: 0x7fffde8fe988

後者好理解，“指標的值”和“存放指標變數的地址”當然不能指望它們是一樣的了，除非這個指標指向它自己！

對於陣列char buff[] = "hello"