| 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.