Array Operators
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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 returns the right-hand array appended to the left-hand array; for keys that exist in both arrays, the elements from the left-hand array will be used, and the matching elements from the right-hand array will be ignored. 

    <?php$a = array("a" => "apple", "b" => "banana");$b = array("a" => "pear", "b" => "strawberry", "c" => "cherry");$c = $a + $b; // Union of $a and $becho "Union of \$a and \$b: \n";var_dump($c);$c = $b + $a; // Union of $b and $aecho "Union of \$b and \$a: \n";var_dump($c);$a += $b; // Union of $a += $b is $a and $becho "Union of \$a += \$b: \n";var_dump($a);?>
    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"
}
Union of $a += $b:
array(3) {
  ["a"]=>
  string(5) "apple"
  ["b"]=>
  string(6) "banana"
  ["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