PHP Manual
Prev | Chapter 15. Operators | Next

# Array Operators

Table 15-8. Array Operators

Example | Name | Result
--- | --- | ---
$a + $b | Union | Union of $a and $b.
$a == $b | Equality | `TRUE` if $a and $b have the same key/value pairs.
$a === $b | Identity | `TRUE` if $a and $b have the same key/value pairs in the same order and of the same types.
$a != $b | Inequality | `TRUE` if $a is not equal to $b.
$a <> $b | Inequality | `TRUE` if $a is not equal to $b.
$a !== $b | Non-identity | `TRUE` if $a is not identical to $b.

The + operator appends the right handed array to the left handed, whereas duplicated keys are NOT overwritten.

`<?php $a = array("a" => "apple", "b" => "banana"); $b = array("a" => "pear", "b" => "strawberry", "c" => "cherry"); $c = $a + $b; // Union of $a and $b echo "Union of \$a and \$b: \n"; var_dump($c); $c = $b + $a; // Union of $b and $a echo "Union of \$b and \$a: \n"; var_dump($c); ?>`

When executed, this script will print the following:

`Union of $a and $b: array(3) { ["a"]=> string(5) "apple" ["b"]=> string(6) "banana" ["c"]=> string(6) "cherry" } Union of $b and $a: array(3) { ["a"]=> string(4) "pear" ["b"]=> string(10) "strawberry" ["c"]=> string(6) "cherry" }`

Elements of arrays are equal for the comparison if they have the same key and value.

Example 15-5. Comparing arrays
`<?php $a = array("apple", "banana"); $b = array(1 => "banana", "0" => "apple"); var_dump($a == $b); // bool(true) var_dump($a === $b); // bool(false) ?>`

See also the manual sections on the Array type and Array functions.

Prev | Home | Next
String Operators | Up | Type Operators