How do you define something so that VScode can assume it is defined (preprocessor)

Question

One of the multiple features of vscode is that when using C or C++ code and we have

#ifdef SOMETHING
this
and this
#endif

if SOMETHING is not defined the code appears shadowed. That is fine and dandy. I know you can set that in the time of building (so my question is not that) but I want to read the code as if SOMETHING is defined. So my question is how can I make VSCode assume that that SOMETHING is defined?

right now I am just putting a comment on the #ifdef but I don't think that is a suitable way of doing this

Answer 1

To start, open the c_cpp_properties.json file for your workspace. This should be in the .vscode folder. If the file doesn't exist, you can create it by opening the command palette with ctrl+shift+p and entering the command C/C++: Edit Configurations (JSON).

Next, add any preprocessor defines to the defines array:

{
  "configurations": [
    {
      "defines": [
        ...
        "YOUR_DEFINE_HERE"
      ],
      ...
    }
  ],
  ...
}

Now, VScode will treat your value(s) as defined and shadow/highlight code appropriately for all C/C++ files in the directory.

You can also add multiple configurations to the c_cpp_properties.json file with different sets of defines. To switch the active configuration, open the command palette and enter C/C++: Select a Configuration.... This is useful for switching between debug and release configurations that may have different sets of defines.