Statement modifiers in Perl

The postfix forms that put if, unless, and for after the statement they guard.

use strict;
use warnings;

my @temps = (18, 21, 35, 12);

# the condition rides behind the statement it guards
print "heat warning\n" if $temps[2] > 30;
print "cold snap\n" unless $temps[3] > 15;
print "$_ degrees\n" for @temps;

my $sum = 0;
$sum += $_ for @temps;
print "average ", $sum / @temps, "\n";

How it works

print ... if and unless guard a single statement with no braces at all.
Postfix for @temps runs the statement once per element, with $_ as the value.
$sum / @temps puts the array in scalar context, so it divides by the count.

Keywords and builtins used here

for
if
my
print
unless
use

The run, in numbers

Lines: 13
Characters to type: 304
Tokens: 75
Three-star pace: 80 tpm

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Step 3 of 3 in Control flow, step 6 of 27 in Language basics.

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