ch7 updated

7_6 to 7_9

Author: tsyw

Diff for: ch7/7_10.cc

@@ -0,0 +1 @@
+// if(read(read(cin, data1), data2))//to judge whether read function get two input 

Diff for: ch7/7_6.h

@@ -0,0 +1,52 @@
+#ifndef EX7_6_H
+#define EX7_6_H
+
+#include <string>
+#include <iostream>
+
+using std::string;
+
+struct Sales_data
+{
+	Sales_data &combine(const Sales_data &);
+	string isbn() const;
+	
+	string bookNo;
+	unsigned units_sold = 0;
+	double revenue = 0.0;
+};
+
+string Sales_data::isbn() const
+{
+	return bookNo;
+}
+
+Sales_data &Sales_data::combine(const Sales_data &trans)
+{
+	units_sold +=trans.units_sold;
+	revenue += trans.revenue;
+	return *this;
+}
+
+Sales_data add(const Sales_data &lhs, const Sales_data &rhs)
+{
+	Sales_data sum = lhs;
+	sum.combine(rhs);
+	return sum;
+}
+
+std::istream &read(std::istream &is, Sales_data &item)
+{
+	double price = 0;
+	is >> item.bookNo >> item.units_sold >> price;
+	item.revenue = price * item.units_sold;
+	return is;
+}
+
+std::ostream &print(std::ostream &os, const Sales_data &item)
+{
+	os << item.isbn() << " " << item.units_sold << " " << item.revenue;
+	return os;
+}
+ 
+ #endif

Diff for: ch7/7_7.cc

@@ -0,0 +1,34 @@
+#include <iostream>
+#include <string>
+#include "7_6.h"
+
+using std::string;
+using std::cin; using std::cout; using std::endl; using std::cerr;
+
+int main()
+{
+	Sales_data total;
+	if(read(cin, total))
+	{
+		Sales_data trans;
+		while(read(cin, trans))
+		{
+			if(total.isbn() == trans.isbn())
+			{
+				total.combine(trans);
+			}
+			else
+			{
+				print(cout, total) << endl;
+				total = trans;
+			}
+		}
+		print(cout, total) << endl;
+	}
+	else
+	{
+		cerr << "No data?!" << endl;
+	}
+
+	return 0;
+}

Diff for: ch7/7_8.cc

@@ -0,0 +1,13 @@
+// std::istream &read(std::istream &is, Sales_data &item)//because read change the Sales_data object item
+// {
+// 	double price = 0;
+// 	is >> item.bookNo >> item.units_sold >> price;
+// 	item.revenue = price * item.units_sold;
+// 	return is;
+// }
+
+// std::ostream &print(std::ostream &os, const Sales_data &item)//print does not change the Sales_data object item
+// {
+// 	os << item.isbn() << " " << item.units_sold << " " << item.revenue;
+// 	return os;
+// }

Diff for: ch7/7_9.cc

@@ -0,0 +1,30 @@
+#ifndef EX7_9_H
+#define EX7_9_H
+
+#include <string>
+#include <iostream>
+
+using std::string;
+
+struct Person
+{
+	string getName() const { return name; }
+	string getAddress() const { return address; }
+
+	string name;
+	string address;
+};
+
+std::istream &read(std::istream &is, Person &item)
+{
+	is >> item.name >> item.address;
+	return is;
+}
+
+std::ostream &print(std::ostream &os, const Person &item)
+{
+	os >> item.getName() >> item.getAddress();
+	return os;
+}
+
+#endif