| #if | used for conditional compilation |
| Syntax | A conditional compilation #if has the form:
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| Description | An #if construct supports compile time selection of sections of source text to make up a program (or unit of a program), in other words conditional compilation. Any arbitrary source text (characters) can be selected. Each of the selecting expressions (expns) have the form of a boolean expression, with the use of the operators and, or and not (but not =>) and parentheses. The short forms & and ~ are supported. The operands of the expressions must be preprocessor flags, which are set by a system- dependent mechanism not described here. A flag is considered to be true if it is explicitly set. If it is not explicitly set, it is considered false. Unlike other parts of the language, the #if, #elsif, #else and #end if constructs are not free format. Specifically, they must be placed by themselves on a single line.
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| Example | A pair of declarations is chosen if both stats and debug are set, otherwise the put statement is selected. The selected part becomes part of the program and the other parts are ignored.
#if stats and debug then
var count : array 1 .. 5 of real
var message : string
#else
put "Debugging message"
#end if
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