Q:

Remove duplicate match from string by regular expression

<?php

function get_video() {

$stripper = "Content...[video=1], content...content...[video=2],
             content...content...content...[video=1], no more...";

preg_match_all("/\[video=(.+?)\]/smi", $stripper, $search);  

$unique = array_unique($search[0]);

$total = count($unique);     
for($i=0; $i < $total; $i++) 
{    
  $vid = $search[1][$i]; 
  if ($vid > 0) 
  {      
    $random_numbers = rand(1, 1000);
    $video_id = $vid."_".$random_numbers;
    $stripper = str_replace($search[0][$i], $video_id, $stripper); 
  } 
} 
return $stripper;
}  

echo get_video();   
?>

I want to remove duplicate [video=1] in $stripper, this is the result i need:
Content...1_195, content...content...2_963, 
content...content...content..., no more...

I am using array_unique() function to remove the duplicate array. From my code above, if i print_r($unique), the duplicate array has been removed:
Array ( [0] => [video=1] [1] => [video=2] )

But if i echo get_video(), the duplicate [video=1] still exist:
Content...1_195, content...content...2_963, 
content...content...content...1_195([video=1]), no more...

I can't figure out why!!! :(
Demo: http://eval.in/7178

A:

To remove duplicates execute a preg_replace_callback and replace the duplicate one by "".  Use the following code just before your preg_match_all call,
$hash = array();
$stripper = preg_replace_callback("/\[video=(.+?)\]/smi",function($m){
    global $hash;
    if(isset($hash[$m[0]]))
        return "";
    else{
        $hash[$m[0]]=1;
        return $m[0];
    }
}, $stripper);   

See http://eval.in/7185

