QB64-PE/internal/help/$LET.txt

[[$LET]] is a precompiler command, which is now usable by modern day [[cavemen]] to help include and exclude which sections of code compiles in their program based on OS/bit-size or other predefined conditions.


{{PageSyntax}}
: [[$LET]] variable = expression


{{PageDescription}}
* Unlike [[LET]], [[$LET]] is not optional.
* $LET a = 12 sets a precompiler variable "a" to the value of 12.   This variable is only valid for the precompiler itself and does nothing to affect the values of any variable/constant which might also be called "a" in the program.
* Variable names can contain numbers, letters, and periods in any order. [[$LET]] '''3.2 = TRUE''' is a perfectly valid variable and expression.
* Expressions can contain one set of leading and/or trailing quotes; and any number of numbers, letters, and periods, in any order. [[$LET]] '''3.2 = "TRUE"''' is also perfectly valid, but [[$LET]] '''3.2 = ""TRUE""''' will error because of the double quotes.
* 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.


{{PageExamples}}
* See example 1 in [[$IF]].


{{PageSeeAlso}}
* [[$IF]]
* [[$ELSE]]
* [[$ELSEIF]]
* [[$END IF]]
* [[Cavemen]]


{{PageNavigation}}