PHP中的多维数组比较

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

Answer 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 .

Answer 2

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

Check this source:

Compare multidimensional arrays in PHP

regards

Answer 3

== 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