How to check a partial similarity of two strings in PHP

Question

Is it any function in PHP that check the % of similarity of two strings?

For example i have:

$string1="Hello how are you doing"  $string2= " hi, how are you" 

and the function($string1, $string2) will return me true because the words "how", "are", "you" are present in the line.

Or even better, return me 60% of similarity because "how", "are", "you" is a 3/5 of $string1.

Does any function exist in PHP which do that?

Answer 1

As it's a nice question, I put some effort into it:

<?php $string1="Hello how are you doing"; $string2= " hi, how are you";  echo 'Compare result: ' . compareStrings($string1, $string2) . '%'; //60%   function compareStrings($s1, $s2) {     //one is empty, so no result     if (strlen($s1)==0 || strlen($s2)==0) {         return 0;     }      //replace none alphanumeric charactors     //i left - in case its used to combine words     $s1clean = preg_replace("/[^A-Za-z0-9-]/", ' ', $s1);     $s2clean = preg_replace("/[^A-Za-z0-9-]/", ' ', $s2);      //remove double spaces     while (strpos($s1clean, "  ")!==false) {         $s1clean = str_replace("  ", " ", $s1clean);     }     while (strpos($s2clean, "  ")!==false) {         $s2clean = str_replace("  ", " ", $s2clean);     }      //create arrays     $ar1 = explode(" ",$s1clean);     $ar2 = explode(" ",$s2clean);     $l1 = count($ar1);     $l2 = count($ar2);      //flip the arrays if needed so ar1 is always largest.     if ($l2>$l1) {         $t = $ar2;         $ar2 = $ar1;         $ar1 = $t;     }      //flip array 2, to make the words the keys     $ar2 = array_flip($ar2);       $maxwords = max($l1, $l2);     $matches = 0;      //find matching words     foreach($ar1 as $word) {         if (array_key_exists($word, $ar2))             $matches++;     }      return ($matches / $maxwords) * 100;     } ?> 

Answer 2

As other answers have already said, you can use similar_text. Here's the demonstration:

$string1="Hello how are you doing" ; $string2= " hi, how are you";  echo similar_text($string1, $string2, $perc); //12  echo $perc; //61.538461538462 

will return 12, and will set in $perc the percentage of similarity as you asked for.