str_get_substrmb($s,$start,$len)

/**
* Returns portion of a string.
*
* @param string $s - the string.
* @param string $start - start point.
* @param string $len - length of sub string.
*/
function str_get_substrmb($s,$start,$len){
if(function_exists('mb_substr')){
$sub = mb_substr($s,$start,$len);
}
else{
$sub = substr($s,$start,$len);
}
return $sub;
}