Multidimensional arrays comparison in PHP

Question

When comparing arrays The Documentation says

$a == $b Equality TRUE if $a and $b have the same key/value pairs.

Though when comparing with multidimensional arrays this doesn’t seem to be the case

$a = array(
  array("test"),
  array("testing"),
);
$b = array(
  array("testing"),
  array("test"),
);

var_dump($a);
var_dump($b);
var_dump($a == $b);

returns

array(2) {
  [0] =>
  array(1) {
    [0] =>
    string(4) "test"
  }
  [1] =>
  array(1) {
    [0] =>
    string(7) "testing"
  }
}
array(2) {
  [0] =>
  array(1) {
    [0] =>
    string(7) "testing"
  }
  [1] =>
  array(1) {
    [0] =>
    string(4) "test"
  }
}
bool(false)

Same array, Different order. array diff returns correctly though.

Is this an expected feature ? I know i can compare with array_diff($a,b) + array($b, $a). Im not sure why the == doesnt work though

Because of the integer keys. Your array is basically `array( 0 => array("test"), 1 => array("testing"))` and `array( 0 => array("testing"), 1 => array("test") );` - which are not the same. — ʰᵈˑ, Mar 18 '15 at 09:24
Argh completely overlooked that, If you make that an answer ill accept it — exussum, Mar 18 '15 at 09:28

score 1 · Accepted Answer · answered Mar 18 '15 at 09:29

1

This is because your arrays are different in the leaf nodes.

In your first array 0 = test and in your second array 0 = testing.

answered Mar 18 '15 at 09:29

ʰᵈˑ

11,279
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score 0 · Answer 2 · edited May 23 '17 at 12:22

0

Use === comparison for taking care about keys order.

Check this source:

Compare multidimensional arrays in PHP

regards

edited May 23 '17 at 12:22

Community

1
1

answered Mar 18 '15 at 09:28

manuelbcd

3,106
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score 0 · Answer 3 · edited May 23 '17 at 12:12

0

== sign allows for comparison of arrays in any order, it will internally use a sort on the master array and do the === comparision.

However it does not do a sort on the sub-arrays, you will need to do that manually before the comparison

NOTE : see == & === difference details here

edited May 23 '17 at 12:12

Community

1
1

answered Mar 18 '15 at 09:29

arkoak

2,437
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35

Multidimensional arrays comparison in PHP

3 Answers3