4.1. "+=" and friends
Perl provides a shortcut for writing "$myvar = $myvar + $value", or "$myvar = $myvar / $value" and similar operations. Here's an example:
$a = 1; $b = 0; print "2^", $b, "=", $a, "\n"; $a *= 2; $b += 1; print "2^", $b, "=", $a, "\n"; $a *= 2; $b += 1; print "2^", $b, "=", $a, "\n"; $a *= 2; $b += 1; print "2^", $b, "=", $a, "\n"; $a *= 2; $b += 1; print "2^", $b, "=", $a, "\n"; $a *= 2; $b += 1; print "2^", $b, "=", $a, "\n";
Since the operations $a += 1 and $a -= 1 are so commonly used, they were also assigned a separate operator. One can use $a++ and $a-- to perform them. For example, the above program could have been written as:
$a = 1; $b = 0; print "2^", $b, "=", $a, "\n"; $a *= 2; $b++; print "2^", $b, "=", $a, "\n"; $a *= 2; $b++; print "2^", $b, "=", $a, "\n"; $a *= 2; $b++; print "2^", $b, "=", $a, "\n"; $a *= 2; $b++; print "2^", $b, "=", $a, "\n"; $a *= 2; $b++; print "2^", $b, "=", $a, "\n";