better print seller no on sale receipt

src/core/seller.cpp

@@ -35,6 +35,15 @@ std::string Seller::getLastName() const { return lastName_; }
 
 int Seller::getSellerNo() const { return sellerNo_; }
 
+std::string Seller::getSellerNoAsString() const 
+{
+    std::stringstream selNoStr;
+    
+    selNoStr << std::setfill('0') << std::setw(3) << sellerNo_;
+
+    return selNoStr.str();;
+}
+
 std::vector<Article*> Seller::getArticles(bool onlySold) const
 {
     std::vector<Article*> articles;

src/core/seller.h

@@ -28,6 +28,7 @@ class Seller : public Entity
     std::string getFirstName() const;
     std::string getLastName() const;
     int getSellerNo() const;
+    std::string getSellerNoAsString() const;
     int numArticlesOffered() const;
     int numArticlesSold() const;
     // int numArticlesTotal() const;

src/printer/posprinter.cpp

@@ -161,7 +161,7 @@ void PosPrinter::printSaleReceipt(Sale* sale)
     commandStream << sale->getTimestampFormatted() << "\n\n";
     commandStream << Command::LEFT_ALIGN;
     for (const auto& article : sale->getArticles()) {
-        commandStream << "Art. " << article->getCompleteArticleNo() << "........... "
+        commandStream << "Verk.Nr. " << article->getSeller()->getSellerNoAsString() << "........... "
                       << article->getPriceAsString() << "\n";
     }
     commandStream << "\nGesamt................. " << sale->sumAsString() << "\n";