> For the complete documentation index, see [llms.txt](https://docs.hex-rays.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.hex-rays.com/8.5/developer-guide/idc/core-concepts/predefined-symbols.md).

# Predefined symbols

The following symbols are predefined in the IDC preprocessor:

```
  _NT_           IDA is running under MS Windows
  _LINUX_        IDA is running under Linux
  _MAC_          IDA is running under Mac OS X
  _UNIX_         IDA is running under Unix (linux or mac)
  _EA64_         64-bit version IDA
  _QT_           GUI version of IDA (Qt)
  _GUI           GUI version of IDA
  _TXT_          Text version of IDA
  _IDA_VERSION_  The current IDA version. For example: "9.1"
  _IDAVER_       The current, numerical IDA version. For example: "900" means v9.0
```

These symbols are also defined when parsing C header files.


---

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