我应该为`size_t'包含哪个标头？

问题描述

根据 size_t 在多个标题中定义，即

 < cstddef> 
< cstdio> 
< cstring> 
< ctime> 
  

而且，由于C ++ 11，还在

 < cstdlib> 
< cwchar> 
  

首先我不知道为什么会出现这种情况。这不是与原则相矛盾吗？但是，我的问题是：

我应该使用以下哪个标头来使用 size_t ？

解决方案

假设我想最小化我导入的函数和类型使用 cstddef ，因为它不声明任何函数，只声明6种类型。

请注意， csttddef 只保证定义 std :: size_t ，即在命名空间中定义 size_t ，尽管 也可以在全局命名空间中提供此名称（有效地， size_t ）。

相反， stddef.h （这也是C中可用的头）保证定义 size_t 在全局命名空间中， 也可提供 std :: size_t 。

According to cppreference.com size_t is defined in several headers, namely

<cstddef>
<cstdio>
<cstring>
<ctime>

And, since C++11, also in

<cstdlib>
<cwchar>

First of all I wonder why this is the case. Isn't this in contradiction to the DRY principle? However, my question is:

Which one of the above headers should I include to use size_t? Does it matter at all?

解决方案

Assuming I wanted to minimize the functions and types I was importing I'd go with cstddef as it doesn't declare any functions and only declares 6 types. The others focus on particular domains (strings, time, IO) that may not matter to you.

Note that csttddef only guarantees to define std::size_t, that is, defining size_t in namespace std, although it may provide this name also in the global namespace (effectively, plain size_t).

In contrast, stddef.h (which is also a header available in C) guarantees to define size_t in the global namespace, and may also provide std::size_t.

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