function substr($str,$start,$len=0) {
		if ($start<0)
			$start=$this->strlen($str)+$start;
		if (!$len)
			$len=$this->strlen($str)-$start;
		return preg_match('/^.{'.$start.'}(.{0,'.$len.'})/us',$str,$match)?
			$match[1]:FALSE;
	}
function substr($str,$start,$len=0) {
		if ($start<0)
			$start=$this->strlen($str)+$start;
		if (!$len)
			$len=$this->strlen($str)-$start;
		return preg_match('/^.{'.$start.'}(.{0,'.$len.'})/us',$str,$match)?
			$match[1]:FALSE;
	}
function substr ( $ str , $ start , $ len = 0 ) { if ( $ start < 0 ) $ start = $ this -> strlen ( $ str ) + $ start ; if ( ! $ len ) $ len = $ this -> strlen ( $ str ) - $ start ; return preg_match ( '/^.{' . $ start . '}(.{0,' . $ len . '})/us' , $ str , $ match ) ? $ match [ 1 ] : FALSE ; }
Return part of a string
@return string|FALSE
@param $str string
@param $start int
@param $len int
Return part of a string