User/jselbie/cppdefaultconstructor (#2)

* added default constructor

* isValid checks for gt zero instead of ne 0

cpp/qrcodegen.cpp

@@ -359,6 +359,18 @@ QrCode::QrCode(int ver, Ecc ecl, const vector<uint8_t> &dataCodewords, int msk)
 }
 
 
+QrCode::QrCode() :
+	version(MIN_VERSION),
+	size(0),
+	mask(0),
+	errorCorrectionLevel(Ecc::LOW) {
+}
+
+
+bool QrCode::isValid() const {
+	return size > 0;
+}
+
 int QrCode::getVersion() const {
 	return version;
 }

cpp/qrcodegen.hpp

@@ -333,10 +333,21 @@ class QrCode final {
 	 */
 	public: QrCode(int ver, Ecc ecl, const std::vector<std::uint8_t> &dataCodewords, int msk);
 	
-	
+	/* 
+     * Default constructor for an uninitialized (empty) QrCode. Useful for when a
+	 * QrCode instance is needed prior to being assigned to. Subsequent calls
+	 * to isValid will return false until a copy assignment is made.
+	 */
+	public: QrCode();	
 	
 	/*---- Public instance methods ----*/
 
+	/* 
+	 * returns false if constructed with the default constructor and not updated with a valid
+     * assignment
+	 */
+    public: bool isValid() const;
+	
 	/* 
 	 * Returns this QR Code's version, in the range [1, 40].
 	 */