Perl 101 (Part 2) - Of Variables And Operators - Comparing Apples And Oranges
(Page 5 of 8 )

In addition to the various arithmetic and string operators, Perl also comes with a bunch of comparison operators, whose sole raison d'etre is to evaluate expressions and determine if they are true or false. Here's a list - you should use these operators for numeric comparisons only.

Assume $x=4 and $y=10

Operator	What It Means	Expression	Result
==	is equal to	$x == $y	False
!=	is not equal to	$x != $y	True
>	is greater than	$x > $y	False
<	is less than	$x < $y	True
>=	is greater than or equal to	$x >= $y	False
<=	is less than or equal to	$x <= $y	True

If, however, you're planning to compare string values, the two most commonly used operators are the equality and inequality operators, as listed below.

Assume $x="abc", $y="xyz"

Operator	What It Means	Expression	Result
eq	is equal to	$x eq $y	False
ne	is not equal to	$x ne $y	True

You can also the greater- and less-than operators for string comparison - however, keep in mind that Perl uses the ASCII values of the strings to be compared when deciding which one is greater.

Assume $x="m", $y="M"

Operator	What It Means	Expression	Result
gt	is greater than	$x gt $y	True
lt	is less than	$x lt $y	False
ge	is greater than or equal to	$x ge $y	True
le	is less than or equal to	$x le $y	False

The reason for this - the ASCII value of "m" is greater than the ASCII value of "M".

This article copyright Melonfire 2000. All rights reserved.

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