compare same array values

Question

What is the best way to compare elments in the same array in PHP, so that if there are two elemets with the same values in array A, I can pass a function as argument to do somthing ?

Solution 1

You can use array_count_values and in_array functions as:

if(in_array(2,array_count_values($array)) {
  // do something
}

Solution 2

If you want to find all values that are duplicated in an array you could do something like this:

// Array to search:
$array = array('one', 'two', 'three', 'one');
// Array to search:
// $array = array('a'=>'one', 'b'=>'two', 'c'=>'three', 'd'=>'one');
// Temp array so we don't find the same key multipule times:
$temp = array();
// Iterate through the array:
foreach ($array as $key)
{
    // Check the key hasn't already been found:
    if (!in_array($key, $temp))
    {
        // Get an array of all the positions of the key:
        $keys = array_keys($array, $key);
        // Check if there is more than one position:
        if (count($keys)>1)
        {
            // Add the key to the temp array so its not found again:
            $temp[] = $key;
            // Do something...
            echo 'Found: "'.$key.'" '.count($keys).' times at position: ';
            for($a=0;$a<count($keys);$a++)
            {
                echo $keys[$a].','; 
            }                   
        }
    }
}

The output from the above would be:

Found: "one" 2 times at positions: 0,3,

If your array had custom keys (as in the commented array) the output would be:

Found: "one" 2 times at positions: a,d,

Solution 3

I assume you wan't to merge to array and then remove duplicates.

$array1 = array('a', 'b', 'c');
$array2 = array(1, 2, 3, 'a');

// array_merge() merges the arrays and array_unique() remove duplicates
var_dump(array_unique(array_merge($array1, $array2)));

// output: array('a', 'b', 'c', 1, 2, 3)

Solution 4

Use array_udiff or similar (with reference arguments in the callback, if you want to be able to modify the values):

$array1 = array('foo', 'bar', 'baz');
$array2 = array('foo', 'baz');

$result = array_udiff($array1, $array2, function(&$a, &$b) {
     if ($a == $b) {
         $a = $b = 'same!';
         return 0;
     }
     return $a > $b ? 1 : -1;
});

print_r($array1); // array('same!', 'bar', 'same!')
print_r($array2); // array('same!', 'same!')

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