Referring to a CMAKE variable from code

Question

I am using `CMAKE 3.4.3` on Windows and what I am trying to do is set a path in CMAKE and try to refer to that in my C++ file. What I tried was as follows: In CMakeLists.txt file ``` ADD_DEFINITIONS(-DNV12_2_ARGB_PTX_DIR "${CMAKE_CURRENT_SOURCE_DIR}/ptx") ``` Now, I try and refer to it from my C++ file as follows: ``` #ifdef NV12_2_ARGB_PTX_DIR #define PTX_DIR D_NV12_2_ARGB_PTX_DIR #endif ``` And when I try to refer to it as: ``` std::cout << PTX_DIR << std::endl; ``` I get the error: ``` 'C:/Users/Luca/project/src/lib/ptx': No such file or directory ``` Also, Visual studio intellisense complains: ``` IntelliSense: identifier "PTX_DIR" is undefined ``` Not sure why it wants to open a file with this variable...

Accepted Answer

The problem is with your use of `add_definitions`. You're effectively passing the value of `${CMAKE_CURRENT_SOURCE_DIR}/ptx` as an additinal argument on the compiler's command line, which the compiler probably interprets as a source file it should compile. Check the full command line invoked to be sure.

You probably intended this:

```
add_definitions(-DNV12_2_ARGB_PTX_DIR="${CMAKE_CURRENT_SOURCE_DIR}/ptx")
```

Note that you may have to play around with escaping the quotation marks to get them all the way down to C++. Alternatively, you could use `configure_file()`.

Referring to a CMAKE variable from code

Solution

Problem