ifdef undef
时间: 2023-08-21 22:15:27 浏览: 174
C 风格的 MATLAB 预处理器:简单,只支持 ifdef/endif/else 和define/undef,&&/|| 的简单语法。-matlab开发
#ifdef undef is a preprocessor directive in the C programming language. It is used to check whether a macro or identifier named "undef" has been defined using the #define directive. If "undef" is defined, the code between #ifdef and #endif will be included for compilation; otherwise, it will be omitted.
For example:
```
#define undef#ifdef undef // Code to be included if "undef" is defined#else // Code to be included if "undef" is not defined#endif```
In this case, since "undef" is defined, the code between the #ifdef and #endif will be included for compilation.
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