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ZBasic Language Reference 76 ZX Microcontroller Family #endif The first form specifies that if the given <identifier> is defined, the compiler should process the text up to the matching #endif but if the <identifier> is not defined, the compiler should ignore the text up to the matching #endif. The second form has the opposite effect. Example #ifdef EXPERIMENTAL Call TestSetup(i) #endif This allows the subroutine call to be compiled into the application if EXPERIMENTAL is defined, otherwise it is left out. As you might have already guessed, the conditional syntax also allows an #else clause. #ifdef EXPERIMENTAL ver = "X006" #else ver = "V1.4" #endif An alternate form of conditional directive allows you to specify an expression involving conditional identifiers and integer or string literals, the Boolean value of which determines whether the code within the conditional block is processed normally or not. #if <expression> <other-text> #elseif <expression> <other-text> #else <other-text> #endif The <expression> element may be any legal ZBasic expression involving constants, conditional identifiers, ZBasic operators and ZBasic System Library functions that can be evaluated at compile time. The usual type-compatibility rules apply, e.g., you cannot add an integral value and a string value. Additionally, the special operator defined() may be used in a conditional expressions. The parameter to the defined() operator should be an identifier and the result will be non-zero or zero depending on whether the identifier is defined or not. Examples #if defined(EXPERIMENTAL) Debug.Print "Experimental version" #endif #if defined(Pin.RedLED) Call PutPin(Pin.RedLED, zxOutputLow) #endif The #elseif clause in the conditional construction may appear zero or more times. The #else clause may appear at most once. The <other-text> element represents arbitrary text and may contain other conditional constructs. There is no practical limit on the nesting of conditionals. Examples #if Version >= 23