_Visual C ++中的_Pragma预处理程序运算符 [英] _Pragma preprocessor operator in Visual C++

问题描述

在Visual C ++中是否有类似ANSI C运算符_Pragma的内容?

Is there something like the ANSI C operator _Pragma in Visual C++?

例如，我正在尝试定义以下宏:

For example, I'm trying to define the following macro:

#ifdef _OPENMP
#define PRAGMA_IF_OPENMP(x) _Pragma (#x)
#else  // #ifdef _OPENMP
#define PRAGMA_IF_OPENMP(x)
#endif  // #ifdef _OPENMP

因此，我可以在较早的GCC编译器中规避针对未知#pragma omp ...的编译器警告. 在VisualC ++中有类似的方法吗?

So I can circumvent compiler warnings for unknown #pragma omp ... in older GCC compilers. Is there a similar means available in VisualC++?

推荐答案

是的，但是有两个下划线:__pragma

Yes, but it's two underscores: __pragma

我不确定omp编译指示的工作方式，但是，下面是使用VC ++的optimize编译指示的示例:

I'm not sure about how the omp pragma works, however, here's an example using VC++'s optimize pragma:

#define PRAGMA_OPTIMIZE_OFF __pragma(optimize("", off))

// These two lines are equivalent
#pragma optimize("", off)
PRAGMA_OPTIMIZE_OFF

编辑:我刚刚确认omp编译指示也可以这样使用:

I've just confirmed that the omp pragmas can also be used like this:

#define OMP_PARALLEL_FOR __pragma(omp parallel for)

因此，是的，如果按如下所示进行定义，您的宏应该可以正常工作(请注意，您的原始代码错误地使用了字符串化运算符#x:

So, yes, your macro should work if defined as follows (note that your original code incorrectly used the stringizing operator #x:

#ifdef _OPENMP
#define PRAGMA_IF_OPENMP(x) __pragma (x)
#else  // #ifdef _OPENMP
#define PRAGMA_IF_OPENMP(x)
#endif  // #ifdef _OPENMP

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