php: check if an array has duplicates

Question

I\'m sure this is an extremely obvious question, and that there\'s a function that does exactly this, but I can\'t seem to find it. In PHP, I\'d like to know if my array has

Answer 1

function hasDuplicate($array){
  $d = array();
  foreach($array as $elements) {
    if(!isset($d[$elements])){
      $d[$elements] = 1;
    }else{
      return true;
    } 
  } 
  return false;
}

Answer 2

You can do it like that way also: This will return true if unique else return false.

$nofollow = (count($modelIdArr) !== count(array_unique($modelIdArr))) ? true : false;

Answer 3

$duplicate = false;

 if(count(array) != count(array_unique(array))){
   $duplicate = true;
}

Answer 4

Here's my take on this… after some benchmarking, I found this to be the fastest method for this.

function has_duplicates( $array ) {
    return count( array_keys( array_flip( $array ) ) ) !== count( $array );
}

…or depending on circumstances this could be marginally faster.

function has_duplicates( $array ) {
    $array = array_count_values( $array );
    rsort( $array );
    return $array[0] > 1;
}

Answer 5

Keep it simple, silly! ;)

Simple OR logic...

function checkDuplicatesInArray($array){
    $duplicates=FALSE;
    foreach($array as $k=>$i){
        if(!isset($value_{$i})){
            $value_{$i}=TRUE;
        }
        else{
            $duplicates|=TRUE;          
        }
    }
    return ($duplicates);
}

Regards!

Answer 6

The simple solution but quite faster.

$elements = array_merge(range(1,10000000),[1]);

function unique_val_inArray($arr) {
    $count = count($arr);
    foreach ($arr as $i_1 => $value) {
        for($i_2 = $i_1 + 1; $i_2 < $count; $i_2++) {
            if($arr[$i_2] === $arr[$i_1]){
                return false;
            }
        }
    }
    return true;
}

$time = microtime(true);
unique_val_inArray($elements);
echo 'This solution: ', (microtime(true) - $time), 's', PHP_EOL;

Speed - [0.71]!