#pragma一旦安全包括警卫？

问题描述：

我已经读过，使用 #pragma once 时会有一些编译器优化，这可能导致更快的编译。我认识到这是非标准的，因此可能构成跨平台兼容性问题。

I've read that there is some compiler optimization when using #pragma once which can result in faster compilation. I recognize that is non-standard, and thus could pose a cross-platform compatibility issue.

这是东西在大多数现代编译器支持非windows平台gcc）

Is this something that is supported by most modern compilers on non-windows platforms (gcc)?

我想避免平台编译问题，但也希望避免后备保护的额外工作：

I want to avoid platform compilation issues, but also want to avoid the extra work of fallback guards:

#pragma once
#ifndef HEADER_H
#define HEADER_H

...

#endif // HEADER_H

我应该关注吗？

答

它应该适用于任何现代编译器，但我没有看到任何原因不使用标准 #ifndef 包含guard。它工作正常。一个警告是，GCC不支持它在版本3.4之前。

It should work on any modern compiler, but I don't see any reason not to use a standard #ifndef include guard. It works just fine. The one caveat is that GCC didn't support it before version 3.4.

我还发现，至少在GCC，它识别标准 #ifndef include guard并优化它，因此它不应该比 #pragma once 慢得多。

I also found that, at least on GCC, it recognizes the standard #ifndef include guard and optimizes it, so it shouldn't be much slower than #pragma once.

#pragma一旦安全包括警卫？

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