Compiler Error CS0179

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'member' cannot be extern and declare a body

When a class member is marked extern, it means that the member's definition is located in another file. Therefore, a class member marked as extern cannot be defined in the class. Either remove the extern keyword or delete the definition. For more information, see Methods (C# Programming Guide).

The following sample generates CS0179:

// CS0179.cs
public class MyClass
{
   public extern int ExternMethod(int aa)   // CS0179
   {
      return 0;
   }
   // try the following line instead
   // public extern int ExternMethod(int aa);

   public static void Main()
   {
   }
}