diff --git a/Ip2Region.php b/Ip2Region.php
index 2167040..196542f 100644
--- a/Ip2Region.php
+++ b/Ip2Region.php
@@ -4,86 +4,85 @@
  *
  * @author  chenxin<chenxin619315@gmail.com>
  * @date    2015-10-29
-*/
+ */
 
-defined('INDEX_BLOCK_LENGTH')   or define('INDEX_BLOCK_LENGTH',  12);
-defined('TOTAL_HEADER_LENGTH')  or define('TOTAL_HEADER_LENGTH', 8192);
+defined('INDEX_BLOCK_LENGTH') or define('INDEX_BLOCK_LENGTH', 12);
+defined('TOTAL_HEADER_LENGTH') or define('TOTAL_HEADER_LENGTH', 8192);
 
-class Ip2Region 
+class Ip2Region
 {
     /**
      * db file handler
-    */
-    private $dbFileHandler = NULL;
+     */
+    private $dbFileHandler = null;
 
     /**
      * header block info
-    */
-    private $HeaderSip    = NULL;
-    private $HeaderPtr    = NULL;
-    private $headerLen  = 0;
+     */
+    private $HeaderSip = null;
+    private $HeaderPtr = null;
+    private $headerLen = 0;
 
     /**
      * super block index info
-    */
+     */
     private $firstIndexPtr = 0;
-    private $lastIndexPtr  = 0;
-    private $totalBlocks   = 0;
+    private $lastIndexPtr = 0;
+    private $totalBlocks = 0;
 
     /**
      * for memory mode only
-     *  the original db binary string
-    */
-    private $dbBinStr = NULL;
-    private $dbFile = NULL;
-    
+     * the original db binary string
+     */
+    private $dbBinStr = null;
+    private $dbFile = null;
+
     /**
      * construct method
      *
-     * @param    ip2regionFile
-    */
-    public function __construct($ip2regionFile = null) 
-	{
+     * @param ip2regionFile
+     */
+    public function __construct($ip2regionFile = null)
+    {
         $this->dbFile = is_null($ip2regionFile) ? __DIR__ . '/ip2region.db' : $ip2regionFile;
     }
 
     /**
      * all the db binary string will be loaded into memory
      * then search the memory only and this will a lot faster than disk base search
-     * @Note: 
+     * @Note:
      * invoke it once before put it to public invoke could make it thread safe
      *
-     * @param   $ip
-    */
+     * @param string $ip
+     * @return array|null
+     * @throws Exception
+     */
     public function memorySearch($ip)
     {
         //check and load the binary string for the first time
-        if ( $this->dbBinStr == NULL ) {
+        if ($this->dbBinStr == null) {
             $this->dbBinStr = file_get_contents($this->dbFile);
-            if ( $this->dbBinStr == false ) {
+            if ($this->dbBinStr == false) {
                 throw new Exception("Fail to open the db file {$this->dbFile}");
             }
-
             $this->firstIndexPtr = self::getLong($this->dbBinStr, 0);
-            $this->lastIndexPtr  = self::getLong($this->dbBinStr, 4);
-            $this->totalBlocks   = ($this->lastIndexPtr-$this->firstIndexPtr)/INDEX_BLOCK_LENGTH + 1;
+            $this->lastIndexPtr = self::getLong($this->dbBinStr, 4);
+            $this->totalBlocks = ($this->lastIndexPtr - $this->firstIndexPtr) / INDEX_BLOCK_LENGTH + 1;
         }
-
-        if ( is_string($ip) ) $ip = self::safeIp2long($ip);
-
+        if (is_string($ip)) $ip = self::safeIp2long($ip);
         //binary search to define the data
         $l = 0;
         $h = $this->totalBlocks;
         $dataPtr = 0;
-        while ( $l <= $h ) {
+        while ($l <= $h) {
             $m = (($l + $h) >> 1);
             $p = $this->firstIndexPtr + $m * INDEX_BLOCK_LENGTH;
             $sip = self::getLong($this->dbBinStr, $p);
-            if ( $ip < $sip ) {
+            if ($ip < $sip) {
                 $h = $m - 1;
             } else {
                 $eip = self::getLong($this->dbBinStr, $p + 4);
-                if ( $ip > $eip ) {
+                if ($ip > $eip) {
                     $l = $m + 1;
                 } else {
                     $dataPtr = self::getLong($this->dbBinStr, $p + 8);
@@ -91,63 +90,57 @@ public function memorySearch($ip)
                 }
             }
         }
-
         //not matched just stop it here
-        if ( $dataPtr == 0 ) return NULL;
-
+        if ($dataPtr == 0) return null;
         //get the data
         $dataLen = (($dataPtr >> 24) & 0xFF);
         $dataPtr = ($dataPtr & 0x00FFFFFF);
-
         return array(
-            'city_id' => self::getLong($this->dbBinStr, $dataPtr), 
-            'region'  => substr($this->dbBinStr, $dataPtr + 4, $dataLen - 4)
+            'city_id' => self::getLong($this->dbBinStr, $dataPtr),
+            'region'  => substr($this->dbBinStr, $dataPtr + 4, $dataLen - 4),
         );
     }
 
     /**
      * get the data block throught the specifield ip address or long ip numeric with binary search algorithm
      *
-     * @param    ip
+     * @param string ip
      * @return    mixed Array or NULL for any error
-    */
-    public function binarySearch( $ip )
+     * @throws Exception
+     */
+    public function binarySearch($ip)
     {
         //check and conver the ip address
-        if ( is_string($ip) ) $ip = self::safeIp2long($ip);
-        if ( $this->totalBlocks == 0 ) {
+        if (is_string($ip)) $ip = self::safeIp2long($ip);
+        if ($this->totalBlocks == 0) {
             //check and open the original db file
-            if ( $this->dbFileHandler == NULL ) {
+            if ($this->dbFileHandler == null) {
                 $this->dbFileHandler = fopen($this->dbFile, 'r');
-                if ( $this->dbFileHandler == false ) {
+                if ($this->dbFileHandler == false) {
                     throw new Exception("Fail to open the db file {$this->dbFile}");
                 }
             }
-
             fseek($this->dbFileHandler, 0);
             $superBlock = fread($this->dbFileHandler, 8);
-
             $this->firstIndexPtr = self::getLong($superBlock, 0);
-            $this->lastIndexPtr  = self::getLong($superBlock, 4);
-            $this->totalBlocks   = ($this->lastIndexPtr-$this->firstIndexPtr)/INDEX_BLOCK_LENGTH + 1;
+            $this->lastIndexPtr = self::getLong($superBlock, 4);
+            $this->totalBlocks = ($this->lastIndexPtr - $this->firstIndexPtr) / INDEX_BLOCK_LENGTH + 1;
         }
-
         //binary search to define the data
         $l = 0;
         $h = $this->totalBlocks;
         $dataPtr = 0;
-        while ( $l <= $h ) {
+        while ($l <= $h) {
             $m = (($l + $h) >> 1);
             $p = $m * INDEX_BLOCK_LENGTH;
-
             fseek($this->dbFileHandler, $this->firstIndexPtr + $p);
             $buffer = fread($this->dbFileHandler, INDEX_BLOCK_LENGTH);
-            $sip    = self::getLong($buffer, 0);
-            if ( $ip < $sip ) {
+            $sip = self::getLong($buffer, 0);
+            if ($ip < $sip) {
                 $h = $m - 1;
             } else {
                 $eip = self::getLong($buffer, 4);
-                if ( $ip > $eip ) {
+                if ($ip > $eip) {
                     $l = $m + 1;
                 } else {
                     $dataPtr = self::getLong($buffer, 8);
@@ -155,128 +148,115 @@ public function binarySearch( $ip )
                 }
             }
         }
-
         //not matched just stop it here
-        if ( $dataPtr == 0 ) return NULL;
-
-
+        if ($dataPtr == 0) return null;
         //get the data
         $dataLen = (($dataPtr >> 24) & 0xFF);
         $dataPtr = ($dataPtr & 0x00FFFFFF);
-
         fseek($this->dbFileHandler, $dataPtr);
         $data = fread($this->dbFileHandler, $dataLen);
-
-        return array(
-            'city_id' => self::getLong($data, 0), 
-            'region'  => substr($data, 4)
-        );
+        return array('city_id' => self::getLong($data, 0), 'region' => substr($data, 4));
     }
 
     /**
      * get the data block associated with the specifield ip with b-tree search algorithm
      * @Note: not thread safe
      *
-     * @param   ip
+     * @param string ip
      * @return  Mixed Array for NULL for any error
-    */
-    public function btreeSearch( $ip )
+     * @throws Exception
+     */
+    public function btreeSearch($ip)
     {
-        if ( is_string($ip) ) $ip = self::safeIp2long($ip);
-
+        if (is_string($ip)) $ip = self::safeIp2long($ip);
         //check and load the header
-        if ( $this->HeaderSip == NULL ) {
+        if ($this->HeaderSip == null) {
             //check and open the original db file
-            if ( $this->dbFileHandler == NULL ) {
+            if ($this->dbFileHandler == null) {
                 $this->dbFileHandler = fopen($this->dbFile, 'r');
-                if ( $this->dbFileHandler == false ) {
+                if ($this->dbFileHandler == false) {
                     throw new Exception("Fail to open the db file {$this->dbFile}");
                 }
             }
-
             fseek($this->dbFileHandler, 8);
             $buffer = fread($this->dbFileHandler, TOTAL_HEADER_LENGTH);
-            
             //fill the header
             $idx = 0;
             $this->HeaderSip = array();
             $this->HeaderPtr = array();
-            for ( $i = 0; $i < TOTAL_HEADER_LENGTH; $i += 8 ) {
+            for ($i = 0; $i < TOTAL_HEADER_LENGTH; $i += 8) {
                 $startIp = self::getLong($buffer, $i);
                 $dataPtr = self::getLong($buffer, $i + 4);
-                if ( $dataPtr == 0 ) break;
+                if ($dataPtr == 0) break;
 
                 $this->HeaderSip[] = $startIp;
                 $this->HeaderPtr[] = $dataPtr;
                 $idx++;
             }
-
             $this->headerLen = $idx;
         }
-        
         //1. define the index block with the binary search
-        $l = 0; $h = $this->headerLen; $sptr = 0; $eptr = 0;
-        while ( $l <= $h ) {
+        $l = 0;
+        $h = $this->headerLen;
+        $sptr = 0;
+        $eptr = 0;
+        while ($l <= $h) {
             $m = (($l + $h) >> 1);
-            
             //perfetc matched, just return it
-            if ( $ip == $this->HeaderSip[$m] ) {
-                if ( $m > 0 ) {
-                    $sptr = $this->HeaderPtr[$m-1];
-                    $eptr = $this->HeaderPtr[$m  ];
+            if ($ip == $this->HeaderSip[$m]) {
+                if ($m > 0) {
+                    $sptr = $this->HeaderPtr[$m - 1];
+                    $eptr = $this->HeaderPtr[$m];
                 } else {
-                    $sptr = $this->HeaderPtr[$m ];
-                    $eptr = $this->HeaderPtr[$m+1];
+                    $sptr = $this->HeaderPtr[$m];
+                    $eptr = $this->HeaderPtr[$m + 1];
                 }
-                
+
                 break;
             }
-            
             //less then the middle value
-            if ( $ip < $this->HeaderSip[$m] ) {
-                if ( $m == 0 ) {
-                    $sptr = $this->HeaderPtr[$m  ];
-                    $eptr = $this->HeaderPtr[$m+1];
+            if ($ip < $this->HeaderSip[$m]) {
+                if ($m == 0) {
+                    $sptr = $this->HeaderPtr[$m];
+                    $eptr = $this->HeaderPtr[$m + 1];
                     break;
-                } else if ( $ip > $this->HeaderSip[$m-1] ) {
-                    $sptr = $this->HeaderPtr[$m-1];
-                    $eptr = $this->HeaderPtr[$m  ];
+                } elseif ($ip > $this->HeaderSip[$m - 1]) {
+                    $sptr = $this->HeaderPtr[$m - 1];
+                    $eptr = $this->HeaderPtr[$m];
                     break;
                 }
                 $h = $m - 1;
             } else {
-                if ( $m == $this->headerLen - 1 ) {
-                    $sptr = $this->HeaderPtr[$m-1];
-                    $eptr = $this->HeaderPtr[$m  ];
+                if ($m == $this->headerLen - 1) {
+                    $sptr = $this->HeaderPtr[$m - 1];
+                    $eptr = $this->HeaderPtr[$m];
                     break;
-                } else if ( $ip <= $this->HeaderSip[$m+1] ) {
-                    $sptr = $this->HeaderPtr[$m  ];
-                    $eptr = $this->HeaderPtr[$m+1];
+                } elseif ($ip <= $this->HeaderSip[$m + 1]) {
+                    $sptr = $this->HeaderPtr[$m];
+                    $eptr = $this->HeaderPtr[$m + 1];
                     break;
                 }
                 $l = $m + 1;
             }
         }
-        
         //match nothing just stop it
-        if ( $sptr == 0 ) return NULL;
-        
+        if ($sptr == 0) return null;
         //2. search the index blocks to define the data
         $blockLen = $eptr - $sptr;
         fseek($this->dbFileHandler, $sptr);
         $index = fread($this->dbFileHandler, $blockLen + INDEX_BLOCK_LENGTH);
-        
         $dataptr = 0;
-        $l = 0; $h = $blockLen / INDEX_BLOCK_LENGTH;
-        while ( $l <= $h ) {
+        $l = 0;
+        $h = $blockLen / INDEX_BLOCK_LENGTH;
+        while ($l <= $h) {
             $m = (($l + $h) >> 1);
             $p = (int)($m * INDEX_BLOCK_LENGTH);
             $sip = self::getLong($index, $p);
-            if ( $ip < $sip ) {
+            if ($ip < $sip) {
                 $h = $m - 1;
             } else {
                 $eip = self::getLong($index, $p + 4);
-                if ( $ip > $eip ) {
+                if ($ip > $eip) {
                     $l = $m + 1;
                 } else {
                     $dataptr = self::getLong($index, $p + 8);
@@ -284,78 +264,67 @@ public function btreeSearch( $ip )
                 }
             }
         }
-        
         //not matched
-        if ( $dataptr == 0 ) return NULL;
-        
+        if ($dataptr == 0) return null;
         //3. get the data
         $dataLen = (($dataptr >> 24) & 0xFF);
         $dataPtr = ($dataptr & 0x00FFFFFF);
-        
         fseek($this->dbFileHandler, $dataPtr);
         $data = fread($this->dbFileHandler, $dataLen);
-
-        return array(
-            'city_id' => self::getLong($data, 0), 
-            'region'  => substr($data, 4)
-        );
+        return array('city_id' => self::getLong($data, 0), 'region' => substr($data, 4));
     }
 
 
     /**
-     * safe self::safeIp2long function 
+     * safe self::safeIp2long function
      *
-     * @param ip 
-     * */
-    public static function safeIp2long($ip) 
+     * @param string ip
+     * @return string
+     */
+    public static function safeIp2long($ip)
     {
         $ip = ip2long($ip);
-
         // convert signed int to unsigned int if on 32 bit operating system
         if ($ip < 0 && PHP_INT_SIZE == 4) {
             $ip = sprintf("%u", $ip);
-        } 
+        }
 
         return $ip;
     }
 
 
-
     /**
      * read a long from a byte buffer
      *
-     * @param    b
-     * @param    offset
-    */
-    public static function getLong( $b, $offset )
+     * @param integer b
+     * @param integer offset
+     * @return string
+     */
+    public static function getLong($b, $offset)
     {
-        $val =  (
-            (ord($b[$offset++]))        | 
-            (ord($b[$offset++]) << 8)   | 
-            (ord($b[$offset++]) << 16)  | 
-            (ord($b[$offset  ]) << 24)
+        $val = (
+            (ord($b[$offset++])) |
+            (ord($b[$offset++]) << 8) |
+            (ord($b[$offset++]) << 16) |
+            (ord($b[$offset]) << 24)
         );
-
         // convert signed int to unsigned int if on 32 bit operating system
         if ($val < 0 && PHP_INT_SIZE == 4) {
             $val = sprintf("%u", $val);
-        } 
-
+        }
         return $val;
     }
 
     /**
      * destruct method, resource destroy
-    */
+     */
     public function __destruct()
     {
-        if ( $this->dbFileHandler != NULL ) {
+        if ($this->dbFileHandler != null) {
             fclose($this->dbFileHandler);
         }
-
-        $this->dbBinStr  = NULL;
-        $this->HeaderSip = NULL;
-        $this->HeaderPtr = NULL;
+        $this->dbBinStr = null;
+        $this->HeaderSip = null;
+        $this->HeaderPtr = null;
     }
 }
-?>
diff --git a/ip2region.db b/ip2region.db
index 564178f..5200feb 100644
Binary files a/ip2region.db and b/ip2region.db differ