v2.6.5: fix gmp extension warning

README.md

@@ -160,7 +160,7 @@ Then just add the following to your `composer.json` file:
 // composer.json
 {
     "require": {
-        "globalcitizen/php-iban": "2.6.4"
+        "globalcitizen/php-iban": "2.6.5"
     }
 }
 ```
@@ -256,7 +256,7 @@ The following table compares __php-iban__ to other PHP projects offering IBAN-re
 
 | Project                                                    | Lic. | Proc | OO  | Began  | Latest | Star | Watch | Fork | Installs | Home culture | Deps    |
 | ---------------------------------------------------------- | ---- | ---- | --- | ------ | ------ | ---- | ----- | ---- | -------- | ------------ | ------- |
-| __php-iban__                                               | LGPL | ✔    | ✔   | 2009   | 2.6.4  | 210  | 23    | 37   | 350k+*   | Global*      | *none*  |
+| __php-iban__                                               | LGPL | ✔    | ✔   | 2009   | 2.6.5  | 210  | 23    | 37   | 350k+*   | Global*      | *none*  |
 | [Iban](https://github.com/jschaedl/Iban)                   | MIT  | ✘    | ✔   | 2013   | 1.3.0  | 50   | 9     | 19   | 178.39k  | German       | lots    |
 | [IsoCodes](https://github.com/ronanguilloux/IsoCodes)      | GPL3 | ✘    | ✔   | 2012   | 2.1.1  | 466  | 22    | 54   | 145k     | French       | lots    |
 | [SepaUtil's](https://github.com/AbcAeffchen/SepaUtilities) | GPL3 | ✘    | ✔   | 2014   | 1.2.3  | 8    | 4     | 3    | 25k      | German       | phpunit |
@@ -330,6 +330,10 @@ Your Help Wanted
 News: March 2018
 ----------------
 
+__[Version 2.6.5](https://github.com/globalcitizen/php-iban/releases/tag/v2.6.5)__ has been released.
+ * Fixed spurious warning when `gmp` extension was enabled
+ * Thanks to @marcovo
+
 __[Version 2.6.4](https://github.com/globalcitizen/php-iban/releases/tag/v2.6.4)__ has been released.
  * Remove spurious dependency on bcmath extension
  * Minor documentation updates

php-iban.php

@@ -148,7 +148,7 @@ function iban_mod97_10_checksum($numeric_representation) {
 function iban_mod97_10($numeric_representation) {
  global $__disable_iiban_gmp_extension;
  # prefer php5 gmp extension if available
- if(!($__disable_iiban_gmp_extension) && function_exists('gmp_intval')) { return gmp_intval(gmp_mod(gmp_init($numeric_representation, 10),'97')) === 1; }
+ if(!($__disable_iiban_gmp_extension) && function_exists('gmp_intval') && $numeric_representation!='') { return gmp_intval(gmp_mod(gmp_init($numeric_representation, 10),'97')) === 1; }
 
 /*
  # old manual processing (~16x slower)