diff --git a/src/Cnp.php b/src/Cnp.php
index c3f07ea..36d2ab6 100644
--- a/src/Cnp.php
+++ b/src/Cnp.php
@@ -1,316 +1,333 @@
-<?php
-
-namespace alcea\cnp;
-
-/**
- * Class Cnp - Validation for Romanian Social Security Number (CNP)
- *
- * Valid format:
- * |S|YY|MM|DD|CC|XXX|C|
- * where :
- * |S|  - Gender number (Male/Women) for:
- *      1/2 - romanian citizen born between 1900.01.01 and 1999.12.31
- *      3/4 - romanian citizen born between 1800.01.01 and 1899.12.31
- *      5/6 - romanian citizen born between 2000.01.01 and 2099.12.31
- *      7/8 - residents
- *      9   - people with foreign citizenship
- *
- * |YY| - year of birth - 00 - 99
- * |MM| - birth month - 01 - 12
- * |DD| - birthday - 01 - 28/29/30/31
- * |CC| - county code - for a valid value check CNP::$countyCode
- * |XXX|- the serial number assigned to the person - 000 - 999
- * |C|  - check Digit
- *
- * ```php
- * use alcea\cnp\Cnp;
- *
- * $cnpToValidate = '5110102441483';
- * $cnp = new Cnp($cnpToValidate);
- * if ($cnp->isValid()) {
- *      // extract info from CNP
- *      echo "CNP {$cnpToValidate} - is valid" . PHP_EOL;
- *      echo "Birth Date: {$cnp->getBirthDateFromCNP('Y/m/d')}" . PHP_EOL;
- *      echo "Birth Place: {$cnp->getBirthCountyFromCNP()}" . PHP_EOL;
- *    echo "Gender: {$cnp->getGenderFromCNP('male', 'female')}" . PHP_EOL;
- * } else {
- *      echo "CNP {$cnpToValidate} is invalid" . PHP_EOL;
- * }
- * ```
- *
- * @see https://ro.wikipedia.org/wiki/Cod_numeric_personal
- * @author Niku Alcea <nicu(dotta)alcea(atta)gmail(dotta)com>
- *
- * @property boolean $_isValid
- * @property array $_cnp
- * @property integer|false $_year
- * @property integer|false $_month
- * @property integer|false $_day
- * @property integer|false $_cc
- * @property integer|false $_serial
- */
-class Cnp
-{
-    private $_isValid = false;
-    private $_cnp = [];
-    private $_year = false;
-    private $_month = false;
-    private $_day = false;
-    private $_cc = false;
-    private $_serial = false;
-    private static $controlKey = [2, 7, 9, 1, 4, 6, 3, 5, 8, 2, 7, 9];
-    private static $countyCode = [
-        '01' => 'Alba',
-        '02' => 'Arad',
-        '03' => 'Arges',
-        '04' => 'Bacau',
-        '05' => 'Bihor',
-        '06' => 'Bistrita-Nasaud',
-        '07' => 'Botosani',
-        '08' => 'Brasov',
-        '09' => 'Braila',
-        '10' => 'Buzau',
-        '11' => 'Caras-Severin',
-        '12' => 'Cluj',
-        '13' => 'Constanta',
-        '14' => 'Covasna',
-        '15' => 'Dambovita',
-        '16' => 'Dolj',
-        '17' => 'Galati',
-        '18' => 'Gorj',
-        '19' => 'Harghita',
-        '20' => 'Hunedoara',
-        '21' => 'Ialomita',
-        '22' => 'Iasi',
-        '23' => 'Ilfov',
-        '24' => 'Maramures',
-        '25' => 'Mehedinti',
-        '26' => 'Mures',
-        '27' => 'Neamt',
-        '28' => 'Olt',
-        '29' => 'Prahova',
-        '30' => 'Satu Mare',
-        '31' => 'Salaj',
-        '32' => 'Sibiu',
-        '33' => 'Suceava',
-        '34' => 'Teleorman',
-        '35' => 'Timis',
-        '36' => 'Tulcea',
-        '37' => 'Vaslui',
-        '38' => 'Valcea',
-        '39' => 'Vrancea',
-        '40' => 'Bucuresti',
-        '41' => 'Bucuresti S.1',
-        '42' => 'Bucuresti S.2',
-        '43' => 'Bucuresti S.3',
-        '44' => 'Bucuresti S.4',
-        '45' => 'Bucuresti S.5',
-        '46' => 'Bucuresti S.6',
-        '51' => 'Calarasi',
-        '52' => 'Giurgiu'
-    ];
-
-    /**
-     * CNP constructor.
-     * @param string $cnp
-     */
-    public function __construct($cnp)
-    {
-        $this->_cnp = str_split(trim($cnp));
-        $this->_isValid = $this->validateCnp();
-    }
-
-    /**
-     * Validation for Romanian Social Security Number (CNP)
-     * @return bool
-     */
-    private function validateCnp()
-    {
-        $cnpArray = $this->_cnp;
-
-        // CNP must have 13 characters
-        if (count($cnpArray) != 13) {
-            return false;
-        }
-
-        // Set and check year, month, day and county
-        if ($this->year() && $this->month() && $this->day() && $this->county()) {
-            $hashArray = self::$controlKey;
-            $hashSum = 0;
-            // All characters must be numeric
-            for ($i = 0; $i <= 12; $i++) {
-                if (!is_numeric($cnpArray[$i])) {
-                    return false;
-                }
-                if ($i < 12) {
-                    $hashSum += (int)$cnpArray[$i] * (int)$hashArray[$i];
-                }
-            }
-
-            $hashSum = $hashSum % 11;
-            if ($hashSum == 10) {
-                $hashSum = 1;
-            }
-
-            return ($cnpArray[12] == $hashSum);
-        }
-
-        return false;
-    }
-
-    /**
-     * Check and set year
-     * @return boolean
-     */
-    private function year()
-    {
-        $cnp = $this->_cnp;
-        $year = ($cnp[1] * 10) + $cnp[2];
-        switch ($cnp[0]) {
-            // romanian citizen born between 1900.01.01 and 1999.12.31
-            case 1 :
-            case 2 :
-                $year += 1900;
-                break;
-            // romanian citizen born between 1800.01.01 and 1899.12.31
-            case 3 :
-            case 4 :
-                $year += 1800;
-                break;
-            // romanian citizen born between 2000.01.01 and 2099.12.31
-            case 5 :
-            case 6 :
-                $year += 2000;
-                break;
-            // residents && people with foreign citizenship
-            case 7 :
-            case 8 :
-            case 9 :
-                $year += 2000;
-                if ($year > (int)date('Y') - 14) {
-                    $year -= 100;
-                }
-                break;
-            default :
-                $year = 0;
-                break;
-        }
-
-        $this->_year = $year;
-
-        return ($year >= 1800) && ($year <= 2099);
-    }
-
-    /**
-     * Check and set month
-     * @return boolean
-     */
-    private function month()
-    {
-        $this->_month = (int)($this->_cnp[3] . $this->_cnp[4]);
-
-        return ($this->_month >= 1) && ($this->_month <= 12);
-    }
-
-    /**
-     * Check and set day
-     * @return boolean
-     */
-    private function day()
-    {
-        $this->_day = (int)($this->_cnp[5] . $this->_cnp[6]);
-
-        if (($this->_day < 1) || ($this->_day > 31)) {
-            return false;
-        }
-
-        if ($this->_day > 28) {
-            // validate date for day of month - 28, 29, 30 si 31
-            if (checkdate($this->_month, $this->_day, $this->_year) === false) {
-                return false;
-            }
-        }
-
-        return true;
-    }
-
-    /**
-     * Check and set county code
-     * @return boolean
-     */
-    private function county()
-    {
-        $this->_cc = (string)($this->_cnp[7] . $this->_cnp[8]);
-
-        return array_key_exists($this->_cc, self::$countyCode);
-    }
-
-    /**
-     *
-     * @return boolean
-     */
-    public function isValid()
-    {
-        return $this->_isValid;
-    }
-
-    /**
-     * Get Birth Place from Romanian Social Security Number (CNP)
-     * @param string|bool $defaultReturn
-     * @return string|bool
-     */
-    public function getBirthCountyFromCNP($defaultReturn = false)
-    {
-        if ($this->_isValid) {
-            return self::$countyCode[$this->_cc];
-        }
-
-        return $defaultReturn;
-    }
-
-    /**
-     * Get Birth Date from Romanian Social Security Number (CNP)
-     * @param string $format
-     * @return string|boolean
-     */
-    public function getBirthDateFromCNP($format = 'Y-m-d')
-    {
-        if ($this->_isValid) {
-            return \DateTime::createFromFormat('Y-m-d', "{$this->_year}-{$this->_month}-{$this->_day}")->format($format);
-        }
-
-        return false;
-    }
-
-    /**
-     * Get gender from Romanian Social Security Number (CNP)
-     * @param string $m
-     * @param string $f
-     * @return string|boolean
-     */
-    public function getGenderFromCNP($m = 'M', $f = 'F')
-    {
-        if ($this->_isValid) {
-            if (in_array($this->_cnp[0], [1, 3, 5, 7])) {
-                return $m;
-            } elseif (in_array($this->_cnp[0], [2, 4, 6, 8])) {
-                return $f;
-            }
-        }
-
-        return false;
-    }
-
-    /**
-     * @return bool|string
-     */
-    public function getSerialNumberFromCNP()
-    {
-        if ($this->_isValid) {
-            return $this->_cnp[9] . $this->_cnp[10] . $this->_cnp[11];
-        }
-
-        return false;
-    }
-
-}
+<?php
+
+namespace alcea\cnp;
+
+/**
+ * Class Cnp - Validation for Romanian Social Security Number (CNP)
+ *
+ * Valid format:
+ * |S|YY|MM|DD|CC|XXX|C|
+ * where :
+ * |S|  - Gender number (Male/Women) for:
+ *      1/2 - romanian citizen born between 1900.01.01 and 1999.12.31
+ *      3/4 - romanian citizen born between 1800.01.01 and 1899.12.31
+ *      5/6 - romanian citizen born between 2000.01.01 and 2099.12.31
+ *      7/8 - residents
+ *      9   - people with foreign citizenship
+ *
+ * |YY| - year of birth - 00 - 99
+ * |MM| - birth month - 01 - 12
+ * |DD| - birthday - 01 - 28/29/30/31
+ * |CC| - county code - for a valid value check CNP::$countyCode
+ * |XXX|- the serial number assigned to the person - 000 - 999
+ * |C|  - check Digit
+ *
+ * ```php
+ * use alcea\cnp\Cnp;
+ *
+ * $cnpToValidate = '5110102441483';
+ * $cnp = new Cnp($cnpToValidate);
+ * if ($cnp->isValid()) {
+ *      // extract info from CNP
+ *      echo "CNP {$cnpToValidate} - is valid" . PHP_EOL;
+ *      echo "Birth Date: {$cnp->getBirthDateFromCNP('Y/m/d')}" . PHP_EOL;
+ *      echo "Birth Place: {$cnp->getBirthCountyFromCNP()}" . PHP_EOL;
+ *    echo "Gender: {$cnp->getGenderFromCNP('male', 'female')}" . PHP_EOL;
+ * } else {
+ *      echo "CNP {$cnpToValidate} is invalid" . PHP_EOL;
+ * }
+ *
+ * // or
+ *
+ * echo "CNP {$cnpToValidate} is " () . Cnp::validate($cnpToValidate) ? 'valid' : 'invalid';
+ *
+ * ```
+ *
+ * @see https://ro.wikipedia.org/wiki/Cod_numeric_personal
+ * @author Niku Alcea <nicu(dotta)alcea(atta)gmail(dotta)com>
+ *
+ * @property boolean $_isValid
+ * @property array $_cnp
+ * @property integer|false $_year
+ * @property integer|false $_month
+ * @property integer|false $_day
+ * @property integer|false $_cc
+ */
+class Cnp
+{
+    private $_isValid = false;
+    private $_cnp = [];
+    private $_year = false;
+    private $_month = false;
+    private $_day = false;
+    private $_cc = false;
+
+    private static $controlKey = [2, 7, 9, 1, 4, 6, 3, 5, 8, 2, 7, 9];
+    private static $countyCode = [
+        '01' => 'Alba',
+        '02' => 'Arad',
+        '03' => 'Arges',
+        '04' => 'Bacau',
+        '05' => 'Bihor',
+        '06' => 'Bistrita-Nasaud',
+        '07' => 'Botosani',
+        '08' => 'Brasov',
+        '09' => 'Braila',
+        '10' => 'Buzau',
+        '11' => 'Caras-Severin',
+        '12' => 'Cluj',
+        '13' => 'Constanta',
+        '14' => 'Covasna',
+        '15' => 'Dambovita',
+        '16' => 'Dolj',
+        '17' => 'Galati',
+        '18' => 'Gorj',
+        '19' => 'Harghita',
+        '20' => 'Hunedoara',
+        '21' => 'Ialomita',
+        '22' => 'Iasi',
+        '23' => 'Ilfov',
+        '24' => 'Maramures',
+        '25' => 'Mehedinti',
+        '26' => 'Mures',
+        '27' => 'Neamt',
+        '28' => 'Olt',
+        '29' => 'Prahova',
+        '30' => 'Satu Mare',
+        '31' => 'Salaj',
+        '32' => 'Sibiu',
+        '33' => 'Suceava',
+        '34' => 'Teleorman',
+        '35' => 'Timis',
+        '36' => 'Tulcea',
+        '37' => 'Vaslui',
+        '38' => 'Valcea',
+        '39' => 'Vrancea',
+        '40' => 'Bucuresti',
+        '41' => 'Bucuresti S.1',
+        '42' => 'Bucuresti S.2',
+        '43' => 'Bucuresti S.3',
+        '44' => 'Bucuresti S.4',
+        '45' => 'Bucuresti S.5',
+        '46' => 'Bucuresti S.6',
+        '51' => 'Calarasi',
+        '52' => 'Giurgiu'
+    ];
+
+    /**
+     * CNP constructor.
+     * @param string|int $cnp
+     */
+    public function __construct($cnp)
+    {
+        try {
+            $this->_cnp = str_split(trim($cnp));
+            $this->_isValid = $this->validateCnp();
+        } catch (\Throwable $e) {
+            $this->_isValid = false;
+        }
+    }
+
+    /**
+     * @param string|int $cnp
+     * @return bool
+     */
+    public static function validate($cnp)
+    {
+        return (new static($cnp))->isValid();
+    }
+
+    /**
+     * Validation for Romanian Social Security Number (CNP)
+     * @return bool
+     */
+    private function validateCnp()
+    {
+        $cnpArray = $this->_cnp;
+
+        // CNP must have 13 characters
+        if (count($cnpArray) != 13) {
+            return false;
+        }
+
+        // Set and check year, month, day and county
+        if ($this->year() && $this->month() && $this->day() && $this->county()) {
+            $hashArray = self::$controlKey;
+            $hashSum = 0;
+            // All characters must be numeric
+            for ($i = 0; $i <= 12; $i++) {
+                if (!is_numeric($cnpArray[$i])) {
+                    return false;
+                }
+                if ($i < 12) {
+                    $hashSum += (int)$cnpArray[$i] * (int)$hashArray[$i];
+                }
+            }
+
+            $hashSum = $hashSum % 11;
+            if ($hashSum == 10) {
+                $hashSum = 1;
+            }
+
+            return ($cnpArray[12] == $hashSum);
+        }
+
+        return false;
+    }
+
+    /**
+     * Check and set year
+     * @return boolean
+     */
+    private function year()
+    {
+        $cnp = $this->_cnp;
+        $year = ($cnp[1] * 10) + $cnp[2];
+        switch ($cnp[0]) {
+            // romanian citizen born between 1900.01.01 and 1999.12.31
+            case 1 :
+            case 2 :
+                $year += 1900;
+                break;
+            // romanian citizen born between 1800.01.01 and 1899.12.31
+            case 3 :
+            case 4 :
+                $year += 1800;
+                break;
+            // romanian citizen born between 2000.01.01 and 2099.12.31
+            case 5 :
+            case 6 :
+                $year += 2000;
+                break;
+            // residents && people with foreign citizenship
+            case 7 :
+            case 8 :
+            case 9 :
+                $year += 2000;
+                if ($year > (int)date('Y') - 14) {
+                    $year -= 100;
+                }
+                break;
+            default :
+                $year = 0;
+                break;
+        }
+
+        $this->_year = $year;
+
+        return ($year >= 1800) && ($year <= 2099);
+    }
+
+    /**
+     * Check and set month
+     * @return boolean
+     */
+    private function month()
+    {
+        $this->_month = (int)($this->_cnp[3] . $this->_cnp[4]);
+
+        return ($this->_month >= 1) && ($this->_month <= 12);
+    }
+
+    /**
+     * Check and set day
+     * @return boolean
+     */
+    private function day()
+    {
+        $this->_day = (int)($this->_cnp[5] . $this->_cnp[6]);
+
+        if (($this->_day < 1) || ($this->_day > 31)) {
+            return false;
+        }
+
+        if ($this->_day > 28) {
+            // validate date for day of month - 28, 29, 30 si 31
+            if (checkdate($this->_month, $this->_day, $this->_year) === false) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * Check and set county code
+     * @return boolean
+     */
+    private function county()
+    {
+        $this->_cc = (string)($this->_cnp[7] . $this->_cnp[8]);
+
+        return array_key_exists($this->_cc, self::$countyCode);
+    }
+
+    /**
+     *
+     * @return boolean
+     */
+    public function isValid()
+    {
+        return $this->_isValid;
+    }
+
+    /**
+     * Get Birth Place from Romanian Social Security Number (CNP)
+     * @param string|bool $defaultReturn
+     * @return string|bool
+     */
+    public function getBirthCountyFromCNP($defaultReturn = false)
+    {
+        if ($this->_isValid) {
+            return self::$countyCode[$this->_cc];
+        }
+
+        return $defaultReturn;
+    }
+
+    /**
+     * Get Birth Date from Romanian Social Security Number (CNP)
+     * @param string $format
+     * @return string|boolean
+     */
+    public function getBirthDateFromCNP($format = 'Y-m-d')
+    {
+        if ($this->_isValid) {
+            return \DateTime::createFromFormat('Y-m-d', "{$this->_year}-{$this->_month}-{$this->_day}")->format($format);
+        }
+
+        return false;
+    }
+
+    /**
+     * Get gender from Romanian Social Security Number (CNP)
+     * @param string $m
+     * @param string $f
+     * @return string|boolean
+     */
+    public function getGenderFromCNP($m = 'M', $f = 'F')
+    {
+        if ($this->_isValid) {
+            if (in_array($this->_cnp[0], [1, 3, 5, 7])) {
+                return $m;
+            } elseif (in_array($this->_cnp[0], [2, 4, 6, 8])) {
+                return $f;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * @return bool|string
+     */
+    public function getSerialNumberFromCNP()
+    {
+        if ($this->_isValid) {
+            return $this->_cnp[9] . $this->_cnp[10] . $this->_cnp[11];
+        }
+
+        return false;
+    }
+
+}
diff --git a/tests/CnpTest.php b/tests/CNPTest.php
similarity index 74%
rename from tests/CnpTest.php
rename to tests/CNPTest.php
index 6e35d0b..62f7b99 100644
--- a/tests/CnpTest.php
+++ b/tests/CNPTest.php
@@ -3,29 +3,41 @@
 use alcea\cnp\Cnp;
 use PHPUnit\Framework\TestCase;
 
-final class CnpTest extends TestCase
+final class CNPTest extends TestCase
 {
 
     public function cnpProvider()
     {
         return [
-            //[CNP, isValid, year, month, day, county, serial]
+            // CNP, isValid, year, month, day, county, serial
+
+            // valid CNP
             [6140101070075, true, 2014, 1, 1, 'F', 'Botosani', '007'],
             ['6140101070075', true, 2014, 1, 1, 'F', 'Botosani', '007'],
             [' 6140101070075', true, 2014, 1, 1, 'F', 'Botosani', '007'],
             [2331214442371, true, 1933, 12, 14, 'F', 'Bucuresti S.4', '237'],
             [1960911123653, true, 1996, 9, 11, 'M', 'Cluj', '365'],
             [3970908055828, true, 1897, 9, 8, 'M', 'Bihor', '582'],
+
+            // invalid CNP
             [1960911123655, false, false, false, false, false, false, false],
             ['123', false, false, false, false, false, false, false],
-            ['614010107007A ', false, false, false, false, false, false, false]
+            ['614010107007A ', false, false, false, false, false, false, false],
+            [false, false, false, false, false, false, false, false],
+            [true, false, false, false, false, false, false, false],
+            [0, false, false, false, false, false, false, false],
+            [-1, false, false, false, false, false, false, false],
+            ['', false, false, false, false, false, false, false],
+            ['xxx', false, false, false, false, false, false, false],
+            [[], false, false, false, false, false, false, false],
+            [new stdClass(), false, false, false, false, false, false, false],
         ];
     }
 
     /**
      * @dataProvider cnpProvider
      */
-    public function testCNP($cnp, $isValid, $year, $month, $day, $sex, $county, $serial)
+    public function test_CNP_is_valid_or_not($cnp, $isValid, $year, $month, $day, $sex, $county, $serial)
     {
         $_cnp = new Cnp($cnp);
 
@@ -38,6 +50,14 @@ public function testCNP($cnp, $isValid, $year, $month, $day, $sex, $county, $ser
         $this->assertEquals($_cnp->getSerialNumberFromCNP(), $serial);
     }
 
+    /**
+     * @dataProvider cnpProvider
+     */
+    public function test_static_CNP_validator($cnp, $isValid, $year, $month, $day, $sex, $county, $serial)
+    {
+        $this->assertEquals($isValid, Cnp::validate($cnp));
+    }
+
     /**
      * TESTCASE - CNP 2910627308894
      * BirthDate: [
@@ -52,7 +72,7 @@ public function testCNP($cnp, $isValid, $year, $month, $day, $sex, $county, $ser
      *
      * @test
      */
-    public function testCNP_2910627308894_IsValid()
+    public function testCNP_2910627308894_is_valid()
     {
         $cnp = new Cnp(2910627308894);
 
@@ -80,7 +100,7 @@ public function testCNP_2910627308894_IsValid()
      *
      * @test
      */
-    public function testCNP_2890905230065_IsValid()
+    public function testCNP_2890905230065_is_valid()
     {
         $cnp = new Cnp(2890905230065);
 
@@ -100,7 +120,7 @@ public function testCNP_2890905230065_IsValid()
     /**
      * @test
      */
-    public function testCNP_22222_IsInvalid()
+    public function testCNP_22222_is_invalid()
     {
         $cnp = new Cnp(22222);
 
@@ -109,5 +129,4 @@ public function testCNP_22222_IsInvalid()
         $this->assertFalse($cnp->getBirthDateFromCNP());
         $this->assertFalse($cnp->getGenderFromCNP());
     }
-
 }