7.3 One-line #if

Syntax:

#if EXPR1 then EXPR2 else EXPR3#

The #if flow-control directive (section 9.4) has a one-line counterpart akin to Perl's and C's ?: operator. If EXPR1 is true, it evaluates EXPR2 and outputs the result (just like #echo EXPR2#). Otherwise it evaluates EXPR3 and outputs that result. This directive is short-circuiting, meaning the expression that isn't needed isn't evaluated.

You MUST include both 'then' and 'else'. If this doesn't work for you or you don't like the style use multi-line #if directives (section 9.4).

The trailing # is the normal end-of-directive character. As usual it may be omitted if there's nothing after the directive on the same line.