#elif lets you create a compound conditional directive. The #elif expression will be evaluated if neither the preceding #if nor any preceding, optional, #elif directive expressions evaluate to true. If a #elif expression evaluates to true, the compiler evaluates all the code between the #elif and the next conditional directive. For example:

#define VC7
//...
#if debug
    Console.Writeline("Debug build");
#elif VC7
    Console.Writeline("Visual Studio 7");
#endif

You can use the operators == (equality), != (inequality), && (and), and || (or), to evaluate multiple symbols. You can also group symbols and operators with parentheses.

 Remarks

#elif is equivalent to using:

#else
#if

Using #elif is simpler, because each #if requires a #endif, whereas a #elif can be used without a matching #endif.

See #if for an example of how to use #elif.

 See Also

Reference

C# Preprocessor Directives

Concepts

C# Programming Guide

Other Resources

C# Reference