3种const指针的区别

const char **p1，只有const常量才能赋值给p1, 可以改变指针的值和指针指向单元的值

char *const *p2，普通变量可以赋值给p2，可以改变指针的值

char **const p3，普通变量可以赋值给p3，可以改变指针指向单元的值

 

后面是一个关于使用数组指针获取元素的范例

 

int _tmain(int argc, _TCHAR* argv[]) { const char *str = "abcd"; const char *str1 = "efg"; char *str2 = "uvw"; char *str3 = "xyz"; char v1 = 'a'; char *pv = &v1; /* const char **p1 */ const char **p1 = &str; //correct //const char **p1 = &str2; //wrong //const char **p1 = &pv; //wrong //*p1 = &str1; //grammar error p1 = &str1; //correct, just p1 point to str2 *p1 = str1; //correct, both str and p1 equal to str1 //**p1 = "ghi"; //wrong /* char *const *p2 */ char *const *p2 = &str2; //correct char *const *p2 = &pv; //correct //char *const *p2 = &str; //wrong p2 = &str3; //correct, just p2 point to str3 //*p2 = str3; //wrong(compare to p1) /* char **const p3 */ char **const p3 = &str2; //correct char **const p3 = &pv; //correct //char **const p3 = &str; //wrong //p3 = &str3; //wrong *p3 = str3; //correct, both str2 and p3 equal to str3 *p3 = pv; //correct, both str2 and p3 pointer to pv /* pointer to array example */ char a[4][3][2] = {​{​{'a','b'},{'c','d'},{'e','f'}}, {​{'g','h'},{'i','j'},{'k','l'}}, {​{'m','n'},{'o','p'},{'q','r'}}, {​{'s','t'},{'u','v'},{'w','x'}}}; char (*pa)[2] = &a[1][0]; //condition char (*ppa)[3][2] = &a[1]; //condition pa = pa + 5; ppa++; char res = (*pa)[1]; //get 'r' by *pa char res1 = (*ppa)[2][1]; //get 'r' by *ppa return 0; }