Most efficient way to compare arrays in PHP by order?

问题

Take these two arrays in PHP:

$array1 = [
    2 => 'Search',
    1 => 'Front-End / GUI'
];
$array2 = [
    1 => 'Front-End / GUI',
    2 => 'Search'
];

Most of the array comparison functions do not care about order. Doing an array_diff will result in an empty array.

What's the most efficient / shortest / cleanest way to compare two arrays with regard to order and:

show whether or not they are equal (true / false)?
show the difference (such as for PHPUnit)?

Running $this->assertEquals( $array1, $array2 ); in PHPUnit ideally should yield something like:

Failed asserting that two arrays are equal.
--- Expected
+++ Actual
@@ @@
 Array (
-    2 => 'Search'
-    1 => 'Front-End / GUI'
+    1 => 'Front-End / GUI'
+    2 => 'Search'
 )

Update - Solution

This generates a sort-of diff only if all elements are same, just in different order. PHPUnit Tests:

public function test...() {
    $actual = someCall();
    $expected = [...];

    // tests for same elements
    $this->assertEquals( $expected, $actual );

    // tests for same order
    $diff = $this->array_diff_order( $expected, $actual );
    $this->assertTrue( $expected === $actual, "Failed asserting that two arrays are equal order.\n--- Expected\n+++ Actual\n@@ @@\n Array(\n$diff )" );
}

private function array_diff_order( $array1, $array2 ) {
    $out = '';
    while ((list($key1, $val1) = each($array1)) && (list($key2, $val2) = each($array2)) ) {
        if($key1 != $key2 || $val1 != $val2) $out .= "-    $key1 => '$val1' \n+    $key2 => '$val2'\n";
    }
    return $out;
}

回答1:

You can just use the === operator

$array = array(1 => "test", 2=> "testing");
$array2 = array(1 => "test", 2=> "testing");

var_dump($array === $array2);

$array2 = array(2 => "test", 1=> "testing");
var_dump($array === $array2);

returns

boolean true
boolean false

then use array_diff_assoc() to find the differences

while ((list($key1, $val1) = each($array)) && (list($key2, $val2) = each($array2)) ) {
    if($key1 != $key2 || $val1 != $val2) echo "- $key1 - $val1 \n + $key2 - $val2";
}

Should give some output for order

Using your array this gives me

2 - Search + 1 - Front-End / GUI
1 - Front-End / GUI + 2 - Search

you can change the output to how ever you need it

回答2:

If you are looking for a solution to generate a diff like output, i think this is a place where iterator shine:

Just having two iterators for each array and stepping trough on them simultaneously in one loop and compare key + value pairs can do almost everything you need:

$array1 = [
    2 => 'Search',
    1 => 'Front-End / GUI'
];
$array2 = [
    1 => 'Front-End / GUI',
    2 => 'Search'
];

$it0 = new ArrayIterator($array1);
$it1 = new ArrayIterator($array2);

while ($it0->valid() || $it1->valid()) {
    if ($it0->valid() && $it1->valid()) {
        if ($it0->key() != $it1->key() || $it0->current() != $it1->current()) {
            print "- ".$it0->key().' => '.$it0->current()."\n";
            print "+ ".$it1->key().' => '.$it1->current()."\n";
        }
        $it0->next();
        $it1->next();
    } elseif ($it0->valid()) {
        print "- ".$it0->key().' => '.$it0->current()."\n";
        $it0->next();
    } elseif ($it1->valid()) {
        print "+ ".$it1->key().' => '.$it1->current()."\n";
        $it1->next();
    }
}

Will output something like:

- 2 => Search
+ 1 => Front-End / GUI
- 1 => Front-End / GUI
+ 2 => Search

This idea of course should be expanded to handle nested arrays with RecursiveArrayIterator and probably format the output better too.

回答3:

You want array_diff_assoc(), which compares values AND keys. array_diff() considers only values.

followup: Works fine here:

php > $arr1 = array(2 => 'Search', 1 => 'Front');
php > $arr2 = array(1 => 'Search', 2 => 'Front');
php > var_dump(array_diff_assoc($arr1, $arr2));
array(2) {
  [2]=>
  string(6) "Search"
  [1]=>
  string(5) "Front"
}

来源：https://stackoverflow.com/questions/17353683/most-efficient-way-to-compare-arrays-in-php-by-order

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