c - 为什么 gcc 中允许空指针运算？

Question

以下代码使用 gcc 编译，尽管 void ptr算术不是标准的:

int main(){
 int a = 5;
 void* b = (void*) &a;
 b++;
}

Answer 1

这是 GCC 支持的扩展。它对待 void *像 char * .

来自 gcc docs :

6.24 Arithmetic on void- and Function-Pointers

In GNU C, addition and subtraction operations are supported on pointers to void and on pointers to functions. This is done by treating the size of a void or of a function as 1.

A consequence of this is that sizeof is also allowed on void and on function types, and returns 1.