copied Company.bankAccountNumber method to base Company class; updated readme with an example

readme.md

@@ -96,6 +96,7 @@ Each of the generator properties (like `name`, `address`, and `lorem`) are calle
     bs                      // 'e-enable robust architectures'
     company                 // 'Bogan-Treutel'
     companySuffix           // 'and Sons'
+    bankAccountNumber($prefix = '', $digitsNumber = 24, $countryCode = 'PL') // 'PL08032566519460083829368443'
 
 ### `Faker\Provider\Lorem`
 

src/Faker/Provider/Company.php

@@ -27,4 +27,33 @@ class Company extends \Faker\Provider\Base
     {
         return static::randomElement(static::$companySuffix);
     }
+
+	/**
+	 * International Bank Account Number (IBAN)
+	 * @link http://en.wikipedia.org/wiki/International_Bank_Account_Number
+	 * @param string $prefix for generating bank account number of a specific bank
+	 * @param integer $digitsNumber total length without country code and 2 check digits
+	 * @param string $countryCode ISO 3166-1 alpha-2 country code
+	 * @return string
+	 */
+	public static function bankAccountNumber($prefix = '', $digitsNumber = 24, $countryCode = 'PL')
+	{
+		$countryCode = strtoupper($countryCode);
+		$result = $prefix;
+		$digitsNumber -= strlen($prefix);
+		for ($i = 0; $i < $digitsNumber; $i++) {
+			$result .= static::randomDigit();
+		}
+		$countryNumber = 100 * (ord($countryCode[0])-55) + (ord($countryCode[1])-55);
+		$tempResult = $result . $countryNumber . '00';
+		// perform MOD97-10 checksum calculation
+		$checksum = (int)$tempResult[0];
+		for ($i = 1; $i < strlen($tempResult); $i++) {
+			$checksum = (10 * $checksum + (int)$tempResult[$i]) % 97;
+		}
+		$checksum = 98 - $checksum;
+		if ($checksum < 10)
+			$checksum = '0'.$checksum;
+		return $countryCode . $checksum . $result;
+	}
 }