Used to control conditional compilation.


#If TargetBoolean [Then]


//Other OS-specific code

[#ElseIf TargetBoolean ]

//Other OS-specific code for this target platform



#If TargetBoolean Then OS-specific code





Boolean constant or Boolean constant expression.

Constant or expression that evaluates to a boolean constant. Used to determine the operating system that will include the code that follows. The following constants are used: DebugBuild XojoVersion Target32Bit Target64Bit TargetARM TargetBigEndian TargetDesktop TargetConsole TargetiOS TargetLinux TargetLittleEndian TargetMacOS TargetMachO TargetMobileDevice TargetMobileSimulator TargetRemoteDebugger TargetWindows TargetWeb TargetX86 TargetXojoCloud


#If statements can be written on one line if there are no #Else or #Elseif clauses. In this case, the Then keyword is required and the #endif is not part of the syntax.

You can use conditional compilation to isolate platform-specific statements such as API calls, AppleEvent routines, or console application routines that are specific to Windows, macOS, or Linux. The code following the #If statement is included only in the build for that operating system.

The optional #ElseIf clause enables you to use a template such as this for handling all cases:

#If TargetWindows Then
  // Windows-specific code here
#ElseIf TargetMacOS
  // Mac-specific code goes here
#ElseIf TargetLinux Then
  // Linux-specific code goes here
#ElseIf TargetXojoCloud Then
  // Xojo Cloud-specific code goes here

The TargetBoolean parameter must be either a Boolean constant or a Boolean constant expression that evaluates to True or False. For example, you can use XojoVersion or XojoVersionString in a boolean expression to check the version currently being used.

#If XojoVersionString = "2018r1" Then
  // Code using features new to this version

Sample code

The following example assigns the file path separator character to a string based on the target platform:

Var separator As String
#If TargetWindows Then
  separator = "\"
#ElseIf TargetMacOS Then
  separator = "/"
#ElseIf TargetLinux Then
  separator = "/"


All project types on all supported operating systems.