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<?    
//------------------------    
// PHPÄÚÖÃ×Ö·û´®º¯ÊýʵÏÖ     
//------------------------    
   
//×Ö·û´®³¤¶È    
function strlen ($str)    
{    
        if ($str == '' ) return 0;    
        $count =  0;    
        while (1){    
                if ( $str[$count] != NULL){    
                         $count++;    
                        continue;    
                }else{    
                        break;    
                }    
        }    
        return $count;    
}    
   
//½ØÈ¡×Ó´®    
function substr($str, $start,  $length=NULL)    
{    
        if ($str== '' || $start>strlen($str )) return;    
    &