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1 files changed, 75 insertions, 0 deletions

diff --git a/7p48.cpp b/7p48.cpp
new file mode 100644
index 0000000..73ba879
--- /dev/null
+++ b/7p48.cpp
@@ -0,0 +1,75 @@
+#include <iostream>
+
+/*
+ *
+ * 7.48
+ *
+ *
+ */
+
+struct SalesData;
+SalesData add(const SalesData&, const SalesData&);
+std::ostream &print(std::ostream&, const SalesData&);
+std::istream &read(std::istream&, SalesData&);
+struct SalesData {
+	SalesData() = default;
+	explicit SalesData(const std::string &s): BookNo(s) { } //constructor, bookNo only
+	SalesData(const std::string &s, unsigned n, double p): // constructor, both bookno, UnitsSold and Revenue
+		BookNo(s), UnitsSold(n), Revenue(p*n) { }
+	explicit SalesData(std::istream &sdcin) { read(sdcin, *this); }; // 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 () {
+
+	// Seems like the same thing happens for explicit and non-explicit
+	
+	std::string null_isbn("9-999-99999-9");
+	SalesData i1(null_isbn);
+	SalesData i2("9-999-99999-9");
+	print(std::cout, i1) << "\n";
+	print(std::cout, i2) << std::endl;
+	return 0;
+}