const char * 和 char *const区别理解

Bjarne在他的The C++ Programming Language里面给出过一个助记的方法：
把一个声明从右向左读。

char  * const cp; ( * 读成 pointer to )
cp is a const pointer to char

const char * p;
p is a pointer to const char;

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测试代码：

#include <stdio.h>

int main( int argc, char *argv[] )
{
    char p[] = "test string";

    const char * p1 = p;  //p1 is a pointer to const char;
    //*(p1 +2 ) = 'L'; // wrong, 内容是常量
    p1 = "new test string p1"; //right,指针可以改


    char * const p2 = p;  //p2 is a const pointer to char
    *(p2 + 2 ) = 'L'; // right , 指针是常量，内容可以修改
    //p2  = "new test string p2"; //wrong, 指针是常量不能修改

    fprintf(stdout, "p1=%s\np2=%s\n", p1, p2);

    return 0;
}