预处理程序指令#error：'已定义DEBUG'

Question

I have the first line in the file as:

#define DEBUG

In my program I have used this variable as:

    #region Preprocessor directives
    #if DEBUG
    #error DEBUG is defined
    #endif
    #endregion

I get this error upon compilation: #error: 'DEBUG is defined' .

Am I mistaking anything?

Answer 1

As I already pointed out in the comments, that is exactly what the `#error' preprocessor directive is intended to do. The description on MSDN says:

#error lets you generate an error from a specific location in your code.

See here on MSDN: https://msdn.microsoft.com/en-us/library/x5hedts0.aspx

So in your case your directive tells the preprocessor to show the error DEBUG is defined when the DEBUG symbol is set.