PHP compare string for duplicatation

Question

I have an array like so:

   array{
    [39] => src="http://www.google.com/jsapi">
    [111] => src="http://www.example.com/wp-content/themes/code.js"
    [55] => src="http://www.example.com/wp-content/themes/yui.js"
    [1015] => src="wp-content/uploads/website.jpg"
   }

Qeustion

What is the best way to find the difference of string ?

What I mean is to check if there are any duplicates.

src="http://www.example.com/wp-content/themes/ is repeated twice.

so if I then had an array like this:

array{
    [39] => src="http://www.google.com/jsapi">
    [55] => src="http://www.example.com/wp-content/themes/yui.js"
    [1015] => src="wp-content/uploads/website.jpg"
   }

http://www. is repeated twice.

so the Idea is to compare the string with another and find something that is duplicated and push it to an array ... thats all that I need :)

I am not saying it could be possible, but it would be nice if it could be :)

Can you clarify a little bit more what you need. Have you tried with regular expressions? You can match duplicates and select them as groups to work on them later... — luben
– luben, Commented Jul 18, 2011 at 16:37
@mellamokb It may not always be the case, [if on second array] google had secure https: then the result would be ://www. is a duplicate :) — Val
– Val, Commented Jul 18, 2011 at 16:40

moteutsch · Accepted Answer · 2011-07-18 16:55:44Z

Community, feel free to optimize the code. I quickly wrote this out.

function findStrDuplicate($str1, $str2)
{
    $duplicate = '';
    for($i = 0; $i < min(strlen($str1), strlen($str2)); $i++) {
        if($str1[$i] != $str2[$i]) {
            break;
        }
        $duplicate .= $str1[$i];
    }

    return $duplicate;
}

function findArrayPrefixDuplicate($array)
{
    $duplicatesArray = array();

    for($i = 0; $i < count($array) - 1; $i++) {
        for($j = $i+1; $j < count($array); $j++) {
            $dup = findStrDuplicate($array[$i], $array[$j]);
            if(!empty($dup)) {
                $duplicatesArray[] = $dup;
            }
        }
    }

    return array_unique($duplicatesArray);
}

$data = array(
    'src="http://www.google.com/jsapi"',
    'src="http://www.example.com/wp-content/themes/code.js"',
    'src="http://www.example.com/wp-content/themes/yui.js"',
    'src="wp-content/uploads/website.jpg"'
);

// Remove src="..."

$data = array_map(function ($val) {
    return substr($val, 5, strlen($val) - 1);
}, $data);

$result = findArrayPrefixDuplicate($data);

var_dump($result);

Result:

array
  0 => string 'http://www.' (length=11)
  2 => string 'http://www.example.com/wp-content/themes/' (length=41)

coreyg · Accepted Answer · 2011-07-18 16:40:50Z

0

The following link should help with this: http://www.rogerethomas.com/b/14/php-search-string-for

You just need to change the else output to add it to the array and add a while loop in there if you are reiterating over multiple entries

answered Jul 18, 2011 at 16:40

coreyg

4288 silver badges19 bronze badges

2 Comments

Val Over a year ago

If I knew the $x there wouldn't be any point asking the question as I have lol, str_replace(); would have done the job :)

coreyg Over a year ago

oh, you are looking at finding the diff and then using that in order to find the dupe, sorry for the confusion

Jacob Eggers · Accepted Answer · 2011-07-18 17:09:21Z

0

I think that you will probably want to take a look at the suffix tree data structure. Take a look at this post for some ideas:

Fast String Search With Suffix Trees

answered Jul 18, 2011 at 17:09

Jacob Eggers

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