New classes added

src/core/article.cpp

@@ -0,0 +1,24 @@
+#include "article.h"
+
+Article::Article() : Entity()
+{}
+
+Article::Article(const std::shared_ptr<Seller> sellerPtr) : Entity()
+{
+    this->sellerPtr = sellerPtr;
+}
+
+void Article::setArticleNo(int articleNo)
+{
+    this->articleNo = articleNo;
+}
+
+void Article::setPrice(int price)
+{
+    this->price = price;
+}
+
+void Article::setDescription(const std::string& description)
+{
+    this->description = description;
+}