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C# - #warning Preprocessor Directive Example

Here, we will use the #warning directive then the program will generate a warning with a specified message after the compilation of the program.
Submitted by Nidhi, on October 31, 2020 [Last updated : March 23, 2023]

Here, we will use the #warning directive then the program will generate a warning with a specified message after the compilation of the program.

C# program to demonstrate the example of #warning preprocessor directive

The source code to demonstrate the #warning preprocessor directive is given below. The given program is compiled and executed successfully on Microsoft Visual Studio.

//C# program to demonstrate the 
//#warning preprocessor directive.

#define MACRO1
#define MACRO2
#define MACRO3
#undef  MACRO2

using System;

class Program
{
   public static void Main()
   {
        #if (!MACRO2)
            #warning MACRO2 is not defined
        #endif
    }
}

Output

Warning	1	#warning: 'MACRO2 is not defined'

Explanation

The above program will generate a warning because here we used the #warning directive with a specified message in the Main() method then the specified message will print as a warning when we compile the program.

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