C# #elif Preprocessing Directive
In this chapter you will learn:
- How to use Preprocessing Directive #elif
- Syntax for #elif Preprocessing Directive
- Example for #elif Preprocessing Directive
Description
The #else directive establishes an alternative if #if fails.
#else marks both the end of the #if block and the beginning of the #else block.
The #elif directive means "else if".
The #elif directive establishes an if-else-if chain for multiple compilation options.
#elif is followed by a symbol expression.
There can be only one #endif associated with any #if.
If the expression is true, that block of code is compiled, and no other #elif expressions are tested.
Syntax
The general form for #elif is
#if symbol-expression
statement sequence /*w w w. j ava 2 s . c om*/
#elif symbol-expression
statement sequence
#elif symbol-expression
statement sequence
#elif symbol-expression
statement sequence
#elif symbol-expression
.
.
.
#endif
Example
Example,
#define AAA /*from w w w.j a va2 s .c o m*/
#define RELEASE
using System;
class MainClass {
public static void Main() {
#if AAA
Console.WriteLine("Compiled for AAA version.");
#elif RELEASE
Console.WriteLine("Compiled for release.");
#else
Console.WriteLine("Compiled for internal testing.");
#endif
#if BBB && !RELEASE
Console.WriteLine("BBB version.");
#endif
Console.WriteLine("This is in all versions.");
}
}
The code above generates the following result.
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