Comparison Operators (Perl and PHP Cross Reference Guide)

General Info: Round Floating Point Numbers

When comparing floating point numbers, make sure you round to an acceptable level of rounding for the type of application you are using.

Languages Focus

A comparison operator compares two values either literals as in "Hello" and 3 or variables as in X and Counter. Most languages use the same operators for comparing both numbers and strings. Perl, for example, uses separate sets of comparison operators for numbers and strings.

Perl:   ==, != Common comparison operators: == equal != not equal < less than > greater than <= less than or equal >= greater than or equal Perl also offers additional string comparison operators: eq string equals ne string not equal lt string less than gt string greater than le string less than or equal ge string greater than or equal Syntax Example: #Does Perl evaluate the math correctly? No! if ((.1 + .1 + .1) == .3) { print("Correct<br>"); } else { print("Not correct<br>"); }

PHP:   ==, != or <> Common comparison operators: == equal != or <> not equal < less than > greater than <= less than or equal >= greater than or equal PHP 4 and above also offers === for indentical (equal plus same type) and !== for not identical (not equal or not same type). Syntax Example: //Does PHP evaluate the math correctly? No! if (.1 + .1 + .1 == .3) { echo "correct"; } else { echo "not correct"; }