使用 __LINE__ 为不同的变量名创建宏

2022-01-11 00:00:00 concatenation macros c++ visual-studio-2010 c-preprocessor

可能重复:
用##和创建C宏LINE(与定位宏的标记连接)

Possible Duplicate:
Creating C macro with ## and LINE (token concatenation with positioning macro)

我正在尝试使用 __LINE__ 宏来生成不同的变量名称.我有一个名为 Benchmark 的范围基准类(位于 utils 命名空间中)，它的构造函数接受一个字符串.这是我创建的宏定义:

I am trying to use the __LINE__ macro to generate different variable names. I have a scoped benchmark class called Benchmark(located in the utils namespace) and it's constructor takes a string. Here is the macro definition I have created:

#define BENCHMARK_SCOPE utils::Benchmark bm##__LINE__(std::string(__FUNCTION__))

不幸的是，这会导致以下错误:

Unfortunately this causes the following error:

<some_file_name>(59):错误 C2374:'bm__LINE__':重新定义；多重初始化

这使我得出结论 __LINE__ 宏没有得到扩展.我根据这篇文章创建了我的宏.你知道为什么 __LINE__ 没有得到扩展吗?

This leads me to the conclusion the __LINE__ macros does not get expanded. I have created my macross according to this post. Do you have ideas why __LINE__ does not get expanded?

编辑:可能编译器信息也是相关的.我正在使用 Visual Studio 2010.

EDIT: probably the compiler info is also relevent. I am using visual studio 2010.

推荐答案

你需要使用2个宏的组合:

You need to use combination of 2 macros:

#define COMBINE1(X,Y) X##Y  // helper macro
#define COMBINE(X,Y) COMBINE1(X,Y)

然后将其用作，

COMBINE(x,__LINE__);

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