Comparing PHP Object Arrays

Question

I need to iterate over two sets of arrays and if they match or do not match then they need to be styled different.

A quick working example is:

$animal1 = array('elephant', 'giraffe', 'lion');
$animal2 = array('elephant', 'giraffe', 'cow');
$animal3 = array('elephant', 'lion', 'giraffe');

foreach($animal1 as $animal) {
    echo $animal . " ";
    if(in_array($animal, $animal2, true)) {
        echo "yay<br />";
    }
    else {
        echo "no<br />";
    }
}

The problem is my that my arrays actually contain objects instead of just data. When I var_dump($example) I'll get something like the following:

array (size=1)
    0 => 
        object(stdClass)[200]
            public 'id' => int 3
            public 'c_name' => string 'AFAM-202-001-2015Spring' (length=23)
            public 'c_avail' => string 'Y' (length=1)
   1 => 
        object(stdClass)[201]
            public 'id' => int 4
            public 'c_name' => string 'IDES-203-001-2015Spring' (length=23)
            public 'c_avail' => string 'Y' (length=1)

So working my $example array into the first example doesn't work. Anyone have any ideas how I can do this? Apparently in_object doesn't exist in PHP ...

Oleg Dubas · Accepted Answer · 2015-01-20 03:19:14Z

0

You can easily convert objects to arrays with (array) type cast.
Say, you have an object $obj.
Do $arr = (array)$obj;
That's it, you have an array with exactly same keys as the property names were.
Everything else's the same!

answered Jan 20, 2015 at 3:19

Oleg Dubas

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IgorAlves · Accepted Answer · 2015-01-20 03:29:44Z

0

The in_array function Checks if a value exists in an array, not objects.

Comparing objects is not the same way to compare values. Look at this Comparing Objects Said that you should change your code

Try this:

foreach ($arr as &$member) {
  if ($member == $obj) {
    return TRUE;
  }
}
return FALSE;

or this:

foreach ($arr as &$member) {
  if ($member === $obj) {
    return TRUE;
  }
}
return FALSE;

Note: you can see how to create a function to compare objects in precedent link Comparing Objects

answered Jan 20, 2015 at 3:29

IgorAlves

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1 Comment

sjagr Over a year ago

A "value" can be an object. The docs for in_array accept a mixed value for the $needle. And your examples are exactly what in_array does, where example #1 is $strict = false and example #2 is $strict = true.

Community · Accepted Answer · 2017-05-23 11:50:50Z

If you're searching for a string to a value within an object found in an array, you could write your own in_array function:

function in_array_of_objects($needle, $haystack, $objValue) {
    foreach ($haystack as $obj) {
        if ($needle === $obj->$objValue) return true;
    }
    return false;
}

Then:

if (in_array_of_objects($animal, $example, 'c_name')) {
    // ...
}

If you want to preserve strict functionality:

function in_array_of_objects($needle, $haystack, $objValue, $strict = false) {
    if ($strict) {
        foreach ($haystack as $obj) {
            if ($needle === $obj->$objValue) return true;
        }
    } else {
        foreach ($haystack as $obj) {
            if ($needle == $obj->$objValue) return true;
        }
    }
    return false;
}

Note I prevented adding the $strict check to the if-statement inside of the foreach loop to cut down on processing time, however marginal it may be.

However, assuming all of the arrays actually contain objects and you're comparing objects with objects, in_array should work if you turn the $strict parameter off...

$test = new stdClass();
$test->one = 'one';
$test->two = 'two';
$test->three = 'three';

$array = array($test, $test, $test, $test); // Same object instance

var_dump(in_array($test, $array, true)); // bool(true)

var_dump(in_array($test, $array)); // bool(true)

$newTest = clone $test; // New object instance, will fail strict checks

var_dump(in_array($newTest, $array, true)); // bool(false)

var_dump(in_array($newTest, $array)); // bool(true)

$newTest = new stdClass();
$newTest->one = 'two';
$newTest->two = 'two';
$newTest->three = 'three';

// To ensure that classes with varying values do not satisfy in_array
var_dump(in_array($newTest, $array)); // bool(false)

However they must still be instances of the same class.

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