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Array Operators

**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 elements of remaining keys from 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 #1 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.