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Methods to determine array equality in PHP and introduction to array operators, array operators_PHP tutorial
- WBOYOriginal
- 2016-07-13 09:59:07873browse
How to determine the equality of arrays in PHP and an introduction to array operators. How do array operators
determine whether two arrays are equal? It’s actually very simple, just use == or ===
The description in the php manual is as follows:
Can multi-dimensional arrays like array('k'=>array()) be equal using the above method? Of course you can.
If the array is numerically indexed, you need to pay attention, see the code:
Copy code The code is as follows:
$a = array("apple", "banana");
$b = array(1 => "banana", "0" => "apple");
var_dump($a == $b); // bool(true)
var_dump($a === $b); // bool(false)
?>
In addition to the array operator ==, there are other more convoluted methods to judge. For example, use array_diff($a, $b) to compare the difference sets of two arrays. If the difference sets are empty arrays, they are equal.
Then let’s talk about the plus operator of arrays. The difference with array_merge is that when equal keys are encountered, when using , the left array will overwrite the value of the right array. On the contrary, with array_merge, the later array will overwrite the previous one.
Copy code The code is as follows:
$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);
$c = array_merge($a, $b); // Union of $b and $a
echo "array_merge of $b and $a: n";
var_dump($c);
?>
Output after execution:
Copy code The code is as follows:
Union of $a and $b:
array(3) {
["a"]=>
string(5) "apple"
["b"]=>
string(6) "banana"
["c"]=>
string(6) "cherry"
}
array_merge of $b and $a:
array(3) {
["a"]=>
string(4) "pear"
["b"]=>
string(10) "strawberry"
["c"]=>
string(6) "cherry"
}