The #if and #endif directives enable conditional compilation.
A symbol is true if it has been defined.
A symbol is false if it has not been defined.
If a symbol has been defined by a #define directive, the symbol true.
The general form of #if is
#if symbol-expression
statement sequence
#endif
#define AAA
using System;
class MainClass {
public static void Main() {
#if AAA
Console.WriteLine("Compiled for experimental version.");
#endif
Console.WriteLine("This is in all versions.");
}
}
Compiled for experimental version.
This is in all versions.