Highlight the matched text using php

Posted at March 5, 2010

We can often see the text being highlighted if the paragraph or text  matches the supplied keyword in many forums and blogs .  We can render this effect using javascript also but here I will go with the simple method of highlighting the matched texts using php .  Using javascript for doing this I think will be little inflexible because all the text has to load before the highlight effect is rendered in the browser.

I have made a simple php class to put this effect into action with two methods in it.

DEMO          FULL SOURCE CODE

<?
/* Author Prabeen Giri <http://prabeengiri.com.np> <prabeen.giri@gmail.com> */		
class HighLightText
{
 // these two consecutive functions are useful for search and customize the found text .
 public function matchAndReplaceText($keyword,$string ,$condition=NULL)
 {
    //if the search Keyword is empty then return with the string  , do not go any further
    if(empty($keyword))
     {
        return $string;
     }
     //omit any html tags if present other wise it will create conflict.
 
     $string = strip_tags($string);
 
     // to check if the search keyword contains space ,it breaks into the words and search for each words.
     $keyword= $this->getArrayofStringWithNoSpace($keyword);
 
     // above function return string either in array or string.
     if(is_array($keyword))
     { 
 
          // replaces the main string with the all the words return by the array of the above functions .
          foreach($keyword as $text)
          { 
 
             if(eregi($text,$string))
             {
                 $string = eregi_replace($text,"<span class='foundText'>".$text."</span>",$string);
             }
          }
 
          return $string;
      }
      // if the above function returns the string then it only check the string with the returned string.
     else
     {
         if(eregi($keyword,$string) and !empty($keyword))
              return eregi_replace($keyword,"<span class='foundText'>".$keyword."</span>",$string);
 
         else
              return $string;
    }
}
 // this function breaks the string by words by finding the whitespace and returns all the words into the array .
 private  function getArrayofStringWithNoSpace($string)
 {
       // checks if the string contains whitespace.
       $newArray = array();
 
       if(eregi(' ',$string))
       { 
 
         //splits the string by whitespace and returns into array
         $ar =  explode(' ',$string); 
 
         foreach($ar  as $val)
         {
             // checks if the array value contais words or white space
             if(!empty($val))
             $newArray[] = $val;
         }
         return $newArray;     
 
       }
        else
        {
             $newArray[] = $string;
             return $newArray;
        }  
   }
}
?>

Now only thing left is to add the css on the matched text and create the instance of above class and invoke its methods.

<style> 
       span.foundText { background:#990000;color:white } 
</style>
<?
 $ht =  new HighLightText(); 
 
 // first parameter is the keyword that needs to be matched and second is the string where the keyword to be searched. 
 echo $ht->matchAndReplaceText($_GET['keyword'] , $string ); 
?>

DEMO          FULL SOURCE CODE

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Php

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