Check and Return Duplicates Array PHP

Check and return duplicates array php

this will be ~100 times faster than array_diff

$dups = array();
foreach(array_count_values($arr) as $val => $c)
    if($c > 1) $dups[] = $val;

How do I find duplicates in a PHP array?

One option is using array_count_values() and include only array elements with more than one values.

$cars = array("Volvo", "BMW", "Toyota", "BMW", "Toyota");

foreach( array_count_values($cars) as $key => $val ) {
    if ( $val > 1 ) $result[] = $key;   //Push the key to the array sice the value is more than 1
}

echo "<pre>";
print_r( $result );
echo "</pre>";

This will result to:

Array
(
    [0] => BMW
    [1] => Toyota
)

Doc: array_count_values()

Check for duplicate entries in array but ONLY return values that are duplicated

Depending on what you want displayed (for example this just gives the ID of a row) it would be better to try it in SQL...

SELECT ID 
    FROM `barcodes` 
    GROUP BY ID 
    HAVING count(ID)>1

The idea is to just retrieve ID's where the count value is more than one.

So this could look like...

$query = mysqli_query($dbc, "SELECT barcode 
    FROM `barcodes` 
    GROUP BY barcode 
    HAVING count(barcode)>1");

$result_array = mysqli_fetch_all($query, MYSQLI_ASSOC);

print_r($result_array);

If you wanted to have the number of times it exists, just add the count to the SELECT list...

SELECT ID, count(ID) times
    FROM `barcodes` 
    GROUP BY ID 
    HAVING count(ID)>1

PHP: How to check if duplicate values in array and keep record of them?

You can do this to detect if you have duplicates

$mergedValues = [];
foreach ($outerArray as $id => $innerArray) {
  $mergedValues = array_merge($mergedValues, $innerArray);
}
$uniqueValues = array_unique($mergedValues);
if (sizeof($uniqueValues) != sizeof($mergedValues)) {
  echo 'You have duplicates!', PHP_EOL;
  echo 'These are duplicates: ', implode(', ', array_unique(array_diff_assoc($mergedValues, $uniqueValues))), PHP_EOL;
}

How to detect duplicate values in PHP array?

You can use array_count_values function

$array = array('apple', 'orange', 'pear', 'banana', 'apple',
'pear', 'kiwi', 'kiwi', 'kiwi');

print_r(array_count_values($array));

will output

Array
(
   [apple] => 2
   [orange] => 1
   [pear] => 2
   etc...
)

php: check if an array has duplicates

You can do:

function has_dupes($array) {
    $dupe_array = array();
    foreach ($array as $val) {
        if (++$dupe_array[$val] > 1) {
            return true;
        }
    }
    return false;
}

php check array value for duplicate

Using array_unique(), this can be easily refactored into a new function:

function array_is_unique($array) {
   return array_unique($array) == $array;
}

Example:

$array = array("a", "a", "b", "c");
echo array_is_unique($array) ? "unique" : "non-unique"; //"non-unique"

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