$LET

$LET is a precompiler command, which helps to include and/or exclude sections of code in a program based on OS/bit-size or other predefined conditions.

Syntax

$LET variable = expression

Description

• Unlike LET, $LET is not optional.
• $LET a = 12 sets a precompiler variable "a" to the value of 12. This variable is only valid for the precompiler itself and does nothing to affect the values of any variable/constant which might also be called "a" in the program.
• Variable names must follow QB64's variable naming conventions.
• You can check a precompiler variable against special values DEFINED and UNDEFINED, in order to assess whether the variable has already been assigned a value. Useful for code in libraries which may be repeated.
• The precompiler comes with some preset values which can be used to help determine which code blocks to include/exclude. These are:
  • WIN or WINDOWS if the user is running QB64 in a Windows environment.
  • LINUX if the user is running QB64 in a Linux environment.
  • MAC or MACOSX if the user is running QB64 in a macOS environment.
  • 32BIT if the user is running a 32-bit version of QB64.
  • 64BIT if the user is running a 64-bit version of QB64.
  • VERSION, which is set to the version of the QB64 compiler.

Examples

• See example 1 in $IF.

See also

• $IF
• $ELSE
• $ELSEIF
• $END IF

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