PHP Function to get Str Pos Nth (Position of nth occurance of a string)

Str Pos N^th (Position of nth occurance of a string)

A handy function to get the position of nth occurance of a substring in a string, with an optional param to make it case insenstive. I am calling it strposnth.

Copyleft : LGPL
Idea by: webKami
Coded By: webKami

Version 1.0.0

Features:
1, Finds nth position of needle in haystack
2, Can perform an case senstive or insenstive operation

 A handy function to get the position of nth occurance
      of a substring in a string, with an optional param to make it case insenstive.
      I am calling it strposnth.

      

    Third optional parameter gets the value of n, e.g puting in 2 will return position
    of second occurance of needle in haystack: Valid inputs (1 = default) 2,3,4..... 

    

    Fourth optional parameter can be used to specify the function as case insenstive:
    Valid inputs (0 = case senstive = default) 1 = case insenstive.

    

    Code:

<?

              

      function strposnth($haystack, $needle, $nth=1, $insenstive=0)

{

   //if its case insenstive, convert strings
into lower case

   if ($insenstive)
{

       $haystack=strtolower($haystack);

       $needle=strtolower($needle);

   }

   //count number of occurances

   $count=substr_count($haystack,$needle);

   

   //first check if the needle exists
in the haystack, return false if it does not

   //also check if asked nth is within the count, return false if it
doesnt

   if ($count<1 || $nth > $count)
return false;



   

   //run a loop to nth number of accurance

   //start $pos from -1, cause we are adding 1 into it while searchig

   //so the very first iteration will be 0

   for($i=0,$pos=0,$len=0;$i<$nth;$i++)

   {    

       //get the position of
needle in haystack

       //provide starting point 0 for first time ($pos=0,
$len=0)

       //provide starting point as position + length of needle
for next time

       $pos=strpos($haystack,$needle,$pos+$len);



       //check the length of
needle to specify in strpos

       //do this only first time

       if ($i==0) $len=strlen($needle);

     }

   

   //return the number

   return $pos;

}



?>

I just construct this function after trying to search a similar one to use in a shopping cart. I am using this to display a limited number of lines or text for featured products. My aim is to limit the product description to 100 characters or 3 lines / 3 list items whichever is less. Example code:

<?

              

      //get the product description from recordset

      $text=$row['product_desc'];

      

      //strip off text if its longer than 100 characters

      if (strlen($text)>100) $text=substr($text,0,100)." ...";

      

      //get ending of the third line

      $pos=strposnth($text,"\n",3,1);

      

      //if found, strip off text after that

      if($pos) $text=substr($text,0,$pos);

      

      //nl2li (new line 2 list) this function converts
      the \n seprated lines of text into sorted or unsorted lists

//I have posted this function in nl2br

//http://uk2.php.net/manual/en/function.nl2br.php

      $text=nl2li($text); 

echo $text;



?>

Examples: strposnth("I am trying to go now.","o"); // returns 13 (strpos behavior) strposnth("I am trying to go now.","O"); // returns false (strpos behavior) strposnth("I am trying to go now.","o",2); // returns 16 (second occurance) strposnth("I am trying to go now.","o",7); // returns false (occurance count is less than 7) strposnth("I am trying to go now.","O",1,1); // returns 13 (stripos behavior) strposnth("I am trying to go now.","O",3,1); // returns 19 (stripos behavior + nth occurance)