1 files changed, 74 insertions, 0 deletions
diff --git a/7p41.cpp b/7p41.cpp
new file mode 100644
index 0000000..12d0916
--- /dev/null
+++ b/7p41.cpp
@@ -0,0 +1,74 @@
+#include <iostream>
+
+/*
+ *
+ * 7.41
+ *
+ *
+ */
+
+struct SalesData;
+SalesData add(const SalesData&, const SalesData&);
+std::ostream &print(std::ostream&, const SalesData&);
+std::istream &read(std::istream&, SalesData&);
+struct SalesData {
+	SalesData(const std::string &s, unsigned n, double p): // constructor, both bookno, UnitsSold and Revenue
+		BookNo(s), UnitsSold(n), Revenue(p*n) { }
+	SalesData(): SalesData("", 0, 0) { std::cout << "delegated\n"; }
+	SalesData(const std::string &s): SalesData(s, 0, 0) { std::cout << "delegated\n"; }
+	SalesData(const std::string &s, unsigned ui): SalesData(s, ui, 0) { std::cout << "delegated\n"; }
+	SalesData(std::istream &sdcin): SalesData() { read(sdcin, *this); std::cout << "delegated\n"; }; // Constructor, but read from istream
+	std::string isbn() const { return BookNo; } // member function
+	SalesData &combine(const SalesData&); // member function, defined elsewhere
+	inline double avg_price() const; // member function, defined elsewhere
+	std::string BookNo; // data member
+	unsigned int UnitsSold = 0; // data member
+	double Revenue = 0.0; // data member
+};
+
+inline double SalesData::avg_price() const {
+
+	if (UnitsSold)
+		return Revenue / UnitsSold;
+	else
+		return 0;
+}
+
+SalesData& SalesData::combine(const SalesData &rhs) {
+
+	UnitsSold += rhs.UnitsSold;
+	Revenue += rhs.Revenue;
+	return *this;
+}
+
+std::istream &read(std::istream &is, SalesData &item) { // Not member function
+
+	double price = 0;
+	is >> item.BookNo >> item.UnitsSold >> price;
+	item.Revenue = price * item.UnitsSold;
+	return is;
+}
+
+std::ostream &print(std::ostream &os, const SalesData &item) { // Not member function
+
+	os << item.isbn() << " " << item.UnitsSold << " "
+	   << item.Revenue << " " << item.avg_price();
+	return os;
+}
+
+SalesData add(const SalesData sd1, const SalesData sd2) { // Not member function
+
+	SalesData sdsum = sd1;
+	sdsum.combine(sd2);
+	return sdsum;
+}
+
+int main () {
+
+	SalesData a;
+	SalesData b("WOW");
+	SalesData c("Woo", 23);
+	SalesData d("Woohoo", 33, 10);
+	SalesData e(std::cin);
+	return 0;
+}