not unique

[Zugzwangle]

how would you write a function to find values from an array that are NOT unique?  'array_unique' finds unique items...

[Mchl]

array_diff($yourArray,array_unique($yourArray));

[Zugzwangle]

I have tried the below:

$uniqueArr = array_diff($thisArray, array_unique($thisArray));
echo print_r($uniqueArr, true);  // returns "Array ( )"

 

I have tried to echo print_r, on the $uniqueArr, but it simply returns "Array ( )". There are definitely duplicates within $thisArray.  What am I doing wrong?

 

[Mchl]

Arrgh... that's because array_unique doesn't do what we thought it was doing. It removes duplicates, not returns unique values.

 

<?php

$a1 = array('a','b','b','c','d','d');
$a2 = array_count_values($a1);
$a3 = array();
foreach($a2 as $key => $value) {
  if($value > 1) {
    $a3[] = $key;
  }
}

print_r($a3);