#if constant expression, #elseif, #else, #endif
Portions of a program may be parsed or be ignored depending on
certain conditions. The pawn parser (compiler or interpreter) gen-
erates code only for those portions for which the condition is true.
The directive #if must be followed by a constant expression. To
check whether a variable or constant is defined, use the defined
operator.
Zero or more #elseif directives may follow the initial #if directive.
These blocks are skipped if any of the preceding #if or #elseif
blocks were parsed (i.e. not skipped). As with the #if directive, a
constant expression must follow the #elseif expression.
The #else causes the parser to skip all lines up to #endif if the pre-
ceding #if or any of the preceding #elseif directives were “true”,
and the parses these lines if all preceding blocks were skipped. The
#else directive may be omitted; if present, there may be only be
one #else associated with each #if.
The #endif directive terminates a program portion that is parsed
conditionally. Conditional directives can be nested and each #if
directive must be ended by an #endif directive.