Simple statements in PERL
The only kind of simple statement is an expression evaluated for
its side effects. Every simple statement must be terminated with
a semicolon, unless it is the final statement in a block, in
which case the semicolon is optional. (Semicolon is still encouraged
there if the block takes up more than one line).
Any simple statement may optionally be followed by a single
modifier, just before the terminating semicolon. The possible
if EXPR unless EXPR
while EXPR until EXPR
The if and unless modifiers have the expected semantics. The
while and until modifiers also have the expected semantics
(conditional evaluated first), except when applied to a
do-BLOCK or a do-SUBROUTINE command, in which case the
block executes once before the conditional is evaluated.
This is so that you can write loops like:
$_ = <STDIN>;
} until $_ eq ".\n";
Please see the do-operator below. Note also that the loop control
commands described later will NOT work in this construct, since
modifiers don't take loop labels. Sorry.
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