Now that you've got the basics of the language down, this secondarticle in the series teaches you about Perl's variables and operators, andalso introduces you to conditional expressions.

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.