将char[][] 赋值给char**的结果

网上一篇文章 char** 和 char[][]的问题引发的讨论, 这里做个笔记。
以下内容部分为网上引用整理。

#include <iostream>using namespace std;int output(char **buf){    printf("    buf address: %p\n",buf);    printf("&buf[0] address: %p\n",&buf[0]);    printf("&buf[1] address; %p\n",&buf[1]);    printf("*buffer address: %p\n",*buf);    printf(" buf[0] address: %p\n",buf[0]);    printf(" buf[1] address: %p\n",buf[1]);    printf("       *buf hex: %lx\n",*buf);    printf(">>> %x%x%x%x%x%x%x%x\n", 'b',' ','a',' ','m','a',' ','i');    printf(">>> %lx\n",buf[0]);    /** 错误 0的说明     * 函数内buf为二级指针，buf[0]类型char*，为指针，64位系统指针8字节，     * 则buf[0]指针的值为buf所指内存单元向下共8个内存单元内容组成的值。     * 这8个内存单元内容是什么呢，就是从函数外buf[0][0]即字符'i'的地址     * 开始依次取八个字节得到的是'i am a b'，将其转化为数值即为0x6d612069，     * 故buf[0]的值为0x6d612069(注意little endian)，printf（“%s\n”,buffer[0]）,故发生地址越界。     *      * 也就是相当于将char *p = "i am a bastard..." 强制转换为char **pp = (char**)p,     * 然后取pp[0], pp[0]就是p的前8个字节。     */    /**     * 错误 0: 执行这句会Crash     */     //printf(">>> %s\n",buf[0]);    printf("\n\n");}int main(){    char buffer[100][1024] = {0};    char *a = "i am a bastard...";    char *b = "hello world...";    int len1 = sprintf(buffer[0],a);    int len2 = sprintf(buffer[1],b);    buffer[0][len1] = '\0';    buffer[1][len2] = '\0';    /************** 0 ***************/    {        printf("       buffer address: %p\n",buffer);        printf("           buffer hex: %x\n",buffer);        printf("   &buffer[0] address: %p\n",&buffer[0]);        printf("   &buffer[1] address: %p\n",&buffer[1]);        printf("&buffer[0][0] address: %p\n",&buffer[0][0]);        printf("a address: %p\n",a);        printf(" a string: %s\n",a);        printf("    a hex: %lx\n",a);        printf("buffer[0]: %s\n",buffer[0]);        printf("buffer[1]: %s\n",buffer[1]);        printf("    a hex: ");        for (int i = 0; i < strlen(a); i++) {            printf("%02hhx",a[i]);        }        printf("\n");        printf("    b hex: ");        for (int i = 0; i < strlen(b); i++) {            printf("%02hhx",b[i]);        }        printf("\n");        output((char **)buffer);    }    /************** 1 ***************/    {        char *p[100];        for(int i=0;i<100;i++) p[i] = buffer[i];        output(p);    }    /************* 2 ***************/    {        char *p[100];        char **pp = p;        for(int i=0;i<100;i++) p[i] = buffer[i];        output(pp);    }    /************* 3 ***************/    {    //c++ 替换为 char **pp = new char*[100];    char **pp = (char **)malloc(sizeof(char *) * 100);     for(int i=0;i<100;i++) pp[i] = buffer[i];    output(pp);    //c++ 替换为 delete[]pp;    free(pp);    }}

Result:       buffer address: 0x7fff5c252c40           buffer hex: 5c252c40   &buffer[0] address: 0x7fff5c252c40   &buffer[1] address: 0x7fff5c253040&buffer[0][0] address: 0x7fff5c252c40a address: 0x103995e80 a string: i am a bastard...    a hex: 103995e80buffer[0]: i am a bastard...buffer[1]: hello world...    a hex: 6920616d206120626173746172642e2e2e    b hex: 68656c6c6f20776f726c642e2e2e    buf address: 0x7fff5c252c40&buf[0] address: 0x7fff5c252c40&buf[1] address; 0x7fff5c252c48*buffer address: 0x622061206d612069 buf[0] address: 0x622061206d612069 buf[1] address: 0x2e2e647261747361       *buf hex: 622061206d612069>>> 622061206d612069>>> 622061206d612069    buf address: 0x7fff5c252920&buf[0] address: 0x7fff5c252920&buf[1] address; 0x7fff5c252928*buffer address: 0x7fff5c252c40 buf[0] address: 0x7fff5c252c40 buf[1] address: 0x7fff5c253040       *buf hex: 7fff5c252c40>>> 622061206d612069>>> 7fff5c252c40    buf address: 0x7fff5c252600&buf[0] address: 0x7fff5c252600&buf[1] address; 0x7fff5c252608*buffer address: 0x7fff5c252c40 buf[0] address: 0x7fff5c252c40 buf[1] address: 0x7fff5c253040       *buf hex: 7fff5c252c40>>> 622061206d612069>>> 7fff5c252c40    buf address: 0x7fc220500000&buf[0] address: 0x7fc220500000&buf[1] address; 0x7fc220500008*buffer address: 0x7fff5c252c40 buf[0] address: 0x7fff5c252c40 buf[1] address: 0x7fff5c253040       *buf hex: 7fff5c252c40>>> 622061206d612069>>> 7fff5c252c40