Refactor 15.2.2

1. fixed 15.7, limit_quote should inherit from bulk_quote class.
2. added the question to README

ch15/README.md

@@ -18,3 +18,31 @@ base class members:
 > Define your own versions of the `Quote` class and the `print_total` function.
 
 [code](ex15_03_Quote.h)
+
+## Exercise 15.4:
+> Which of the following declarations, if any, are incorrect? Explain why.
+```cpp
+class Base { ... };
+(a) class Derived : public Derived { ... };
+(b) class Derived : private Base { ... };
+(c) class Derived : public Base;
+```
+
+- (a) incorrect, derive from itself
+- (b) incorrect, this is a definition not a declaration
+- (c) incorrect, A derived class is declared like any other class. The declaration contains the class name but does not include its derivation list
+
+## Exercise 15.5:
+> Define your own version of the `Bulk_quote` class.
+
+[code](ex15_05_Bulk_quote.h)
+
+## Exercise 15.6:
+> Test your `print_total` function from the exercises in 15.2.1 (p. 595) by passing both `Quote` and `Bulk_quote` objects o that function.
+
+[TEST](TEST.cpp)
+
+## Exercise 15.7:
+> Define a class that implements a limited discount strategy, which applies a discount to books purchased up to a given limit. If the number of copies exceeds that limit, the normal price applies to those purchased beyond the limit.
+
+[code](ex15_07_Limit_quote.h)

ch15/TEST.cpp

@@ -5,4 +5,10 @@ int main()
 {
     EX03::Quote quote_03("0-201-78345-X", 23.8);
     EX03::print_total(std::cout, quote_03, 3);
+
+    EX05::Bulk_quote bulk_quote("0-201-78345-X", 23.8, 3, 0.5);
+    EX03::print_total(std::cout, bulk_quote, 4);
+
+    EX07::Limit_quote limit_quote("0-201-78345-X", 23.8, 3, 5, 0.5);
+    EX03::print_total(std::cout, limit_quote, 6);
 }

ch15/ch15.h

@@ -18,6 +18,8 @@ If you have questions, try to connect with me: pezy<[email protected]>
 
 namespace ch15 {
 #include "ex15_03_Quote.h"
+#include "ex15_05_Bulk_quote.h"
+#include "ex15_07_Limit_quote.h"
 }
 
 #endif // CH15_H_

ch15/ex15_05_Bulk_quote.h

@@ -0,0 +1,39 @@
+/*
+=================================================================================
+
+C++ Primer 5th Exercise Answer Source Code
+Copyright (C) 2014-2015 github.com/pezy/Cpp-Primer
+
+Bulk_quote class
+
+If you have questions, try to connect with me: pezy<[email protected]>
+
+=================================================================================
+*/
+
+#ifndef BULK_QUOTE_H_
+#define BULK_QUOTE_H_
+
+#include "ex15_03_Quote.h"
+#include <string>
+
+namespace EX05 {
+    using std::string;
+    using namespace EX03;
+
+class Bulk_quote : public Quote {
+public:
+    Bulk_quote() = default;
+    Bulk_quote(string const& book, double p, size_t qty, double disc) : Quote(book, p), min_qty(qty), discount(disc) {}
+
+    virtual double net_price(size_t cnt) const override {
+        if (cnt >= min_qty) return cnt * (1 - discount) * price;
+        else return cnt * price;
+    }
+protected:
+    size_t min_qty = 0;
+    double discount = 0.0;
+};
+}
+
+#endif // BULK_QUOTE_H_

ch15/ex15_07_Limit_quote.h

@@ -0,0 +1,40 @@
+/*
+=================================================================================
+
+C++ Primer 5th Exercise Answer Source Code
+Copyright (C) 2014-2015 github.com/pezy/Cpp-Primer
+
+Limit_quote class
+
+If you have questions, try to connect with me: pezy<[email protected]>
+
+=================================================================================
+*/
+
+#ifndef LIMIT_QUOTE_H_
+#define LIMIT_QUOTE_H_
+
+#include "ex15_05_Bulk_quote.h"
+#include <string>
+
+namespace EX07 {
+    using namespace EX05;
+    using std::string;
+
+class Limit_quote : public Bulk_quote {
+public:
+    Limit_quote() = default;
+    Limit_quote(string const& book, double p, size_t min, size_t max, double dist) : Bulk_quote(book, p, min, dist), max_qty(max) {}
+
+    double net_price(size_t cnt) const override {
+        if (cnt > max_qty) return max_qty * (1 - discount) * price + (cnt - max_qty) * price;
+        else if (cnt >= min_qty) return cnt * (1 - discount) * price;
+        else return cnt * price;
+    }
+
+private:
+    size_t max_qty = 0;
+};
+}
+
+#endif // LIMIT_QUOTE_H_