c:空隙大小* [英] c: size of void*

问题描述

我对 C 中的 void* 指针有点困惑.尤其是在阅读了这个问题之后:sizeof(some pointer) 总是等于四吗?，其中有人说不能保证 sizeof(int *) == sizeof(double *)

I'm a bit confused with a void* pointer in C. Especially after reading this question: Is the sizeof(some pointer) always equal to four?, where one person says there is no guarantee that sizeof(int *) == sizeof(double *)

我的问题是:是否有 sizeof(void*) >= sizeof(任何其他指针类型)的保证?换句话说，我可以总是将 some_type* 指针分配给 void* 指针，然后将其作为 some_type* 取回吗?

My question is: is there a guarantee of sizeof(void*) >= sizeof(any other pointer type)? In other words, can I always assign a some_type* pointer to a void* pointer and then get it back as some_type*?

推荐答案

仅数据指针.void * 可以存放任何数据指针，但不能存放函数指针.

Only data pointers. void * can hold any data pointer, but not function pointers.

这是 C 常见问题解答.

void *'s 只保证保存对象(即数据)指针；它将函数指针转换为 void * 类型是不可移植的.(一些机器，函数地址可以非常大，比任何数据都大指针.)

void *'s are only guaranteed to hold object (i.e. data) pointers; it is not portable to convert a function pointer to type void *. (On some machines, function addresses can be very large, bigger than any data pointers.)

至于第一部分，是的，不同类型可以有不同大小的指针:

As for the first part, yes, different types can have pointers of different sizes:

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