strripos

Simple way to implement this function in PHP 4<?phpif (function_exists('strripos') == false) {    function strripos($haystack, $needle) {        return strlen($haystack) - strpos(strrev($haystack), $needle);    }}?>

Suppose you just need a stripos function working backwards expecting that strripos does this job, you better use the following code of a custom function named strbipos:<?phpfunction strbipos($haystack="", $needle="", $offset=0) {// Search backwards in $haystack for $needle starting from $offset and return the position found or false    $len = strlen($haystack);    $pos = stripos(strrev($haystack), strrev($needle), $len - $offset - 1);    return ( ($pos === false) ? false : $len - strlen($needle) - $pos );}// Test$body = "01234Xy7890XYz456xy90";$str = "xY";$len = strlen($body);echo "TEST POSITIVE offset VALUES IN strbipos<br>";for ($i = 0; $i < $len; $i++) {    echo "Search in [$body] for [$str] starting from offset [$i]: [" . strbipos($body, $str, $i) . "]<br>";}?>Note that this function does exactly what it says and its results are different comparing to PHP 5 strripos function.

I think you shouldn't underestimate the length of $needle in the search of THE FIRST POSITION of it's last occurrence in the string. I improved the posted function, with added support for offset. I think this is an exact copy of the real function:<?phpif(!function_exists("strripos")){    function strripos($haystack, $needle, $offset=0) {        if($offset<0){            $temp_cut = strrev(  substr( $haystack, 0, abs($offset) )  );        }        else{            $temp_cut = strrev(  substr( $haystack, $offset )  );        }        $pos = strlen($haystack) - (strpos($temp_cut, strrev($needle)) + $offset + strlen($needle));        if ($pos == strlen($haystack)) { $pos = 0; }        return $pos;    }/* endfunction strripos*/}/* endfunction exists strripos*/?>

OK, I guess this will be the final function implementation for PHP 4.x versions ( my previous posts are invalid )<?phpif(!function_exists("stripos")){    function stripos(  $str, $needle, $offset = 0  ){        return strpos(  strtolower( $str ), strtolower( $needle ), $offset  );    }/* endfunction stripos */}/* endfunction exists stripos */if(!function_exists("strripos")){    function strripos(  $haystack, $needle, $offset = 0  ) {        if(  !is_string( $needle )  )$needle = chr(  intval( $needle )  );        if(  $offset < 0  ){            $temp_cut = strrev(  substr( $haystack, 0, abs($offset) )  );        }        else{            $temp_cut = strrev(    substr(   $haystack, 0, max(  ( strlen($haystack) - $offset ), 0  )   )    );        }        if(   (  $found = stripos( $temp_cut, strrev($needle) )  ) === FALSE   )return FALSE;        $pos = (   strlen(  $haystack  ) - (  $found + $offset + strlen( $needle )  )   );        return $pos;    }/* endfunction strripos */}/* endfunction exists strripos */?>

Generally speaking, linear searches are from start to end, not end to start - which makes sense from a human perspective. If you need to find strings in a string backwards, reverse your haystack and needle rather than manually chopping it up.

Sorry, I made that last post a bit prematurely.  One more thing wrong with the simple php4 version is that it breaks if the string is not found.  It should actually look like this:<?phpif (function_exists('strripos') == false) {    function strripos($haystack, $needle) {        $pos = strlen($haystack) - strpos(strrev($haystack), strrev($needle));        if ($pos == strlen($haystack)) { $pos = 0; }        return $pos;    }}?>Note, we now check to see if the $needle was found, and if it isn't, we return 0.