Array Operators

Table 10-7. Array Operators

Example	Name	Result
$a + $b	Union	Union of $a and $b.
$a == $b	Equality	`TRUE` if $a and $b have the same elements.
$a === $b	Identity	`TRUE` if $a and $b have the same elements in the same order.
$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 10-2. 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.