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";