Add soultions to second half of exercises in chapter 15.

Author: Jaege

README.md

@@ -143,11 +143,11 @@ This repo is the solutions to exercises in book [_C++ Primer_ (5th Edition)](htt
 
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-[1](ch15/15.1.cpp)|[2](ch15/15.2.cpp)|[3](ch15/15.3.cpp)|[4](ch15/15.4.cpp)|[5](ch15/15.5.cpp)|[6](ch15/15.6.cpp)|[7](ch15/15.7.cpp)|[8](ch15/15.8.cpp)|[9](ch15/15.9.cpp)|[10](ch15/15.10.cpp)|
-[11](ch15/15.11.cpp)|[12](ch15/15.12.cpp)|[13](ch15/15.13.cpp)|[14](ch15/15.14.cpp)|[15](ch15/15.15.cpp)|[16](ch15/15.16.cpp)|[17](ch15/15.17.cpp)|[18](ch15/15.18.cpp)|[19](ch15/15.19.cpp)|[20](ch15/15.20.cpp)|
-[21](ch15/15.21.cpp)|[22](ch15/15.22.cpp)|[23](ch15/15.23.cpp)|[24](ch15/15.24.cpp)|[25](ch15/15.25.cpp)|[26](ch15/15.26.cpp)|[27](ch15/15.27.cpp)|[28](ch15/15.28.cpp)|[29](ch15/15.29.cpp)|[30](ch15/15.30.cpp)|
-[31](ch15/15.31.cpp)|[32](ch15/15.32.cpp)|[33](ch15/15.33.cpp)|[34](ch15/15.34.cpp)|[35](ch15/15.35.cpp)|[36](ch15/15.36.cpp)|[37](ch15/15.37.cpp)|[38](ch15/15.38.cpp)|[39](ch15/15.39.cpp)|[40](ch15/15.40.cpp)|
-[41](ch15/15.41.cpp)|[42](ch15/15.42.cpp)
+[1](ch15/15.1.md)|[2](ch15/15.2.md)|[3](ch15/15.3.cpp)|[4](ch15/15.4.md)|[5](ch15/15.5.md)|[6](ch15/15.6.md)|[7](ch15/15.7.cpp)|[8](ch15/15.8.md)|[9](ch15/15.9.md)|[10](ch15/15.10.md)|
+[11](ch15/15.11.cpp)|[12](ch15/15.12.md)|[13](ch15/15.13.md)|[14](ch15/15.14.cpp)|[15](ch15/15.15.cpp)|[16](ch15/15.16.md)|[17](ch15/15.17.cpp)|[18](ch15/15.18.cpp)|[19](ch15/15.19.cpp)|[20](ch15/15.20.md)|
+[21](ch15/15.21.cpp)|[22](ch15/15.22.cpp)|[23](ch15/15.23.cpp)|[24](ch15/15.24.md)|[25](ch15/15.25.md)|[26](ch15/15.26.cpp)|[27](ch15/15.27.cpp)|[28](ch15/15.28.cpp)|[29](ch15/15.29.cpp)|[30](ch15/15.30.cpp)|
+[31](ch15/15.31.md)|[32](ch15/15.32.md)|[33](ch15/15.33.md)|[34](ch15/15.34.md)|[35](ch15/15.35)|[36](ch15/15.36.md)|[37](ch15/15.37)|[38](ch15/15.38.md)|[39](ch15/15.39)|[40](ch15/15.40.md)|
+[41](ch15/15.41)|[42](ch15/15.42)
 
 <!---
 #### Chapter 16 [Templates and Generic Programming](ch16)

ch15/15.23.cpp

@@ -0,0 +1,33 @@
+#include <iostream>
+using std::cout; using std::endl;
+
+class Base {
+public:
+  virtual int fcn() { cout << "Base::fcn" << endl; return 0; }
+};
+
+class D1 : public Base {
+public:
+  //int fcn(int);
+  int fcn() override {  // fixed by removing parameter and add keyword override
+    cout << "D1::fcn" << endl; return 0;
+  }
+  virtual void f2() { cout << "D1::f2" << endl; }
+};
+
+class D2 : public D1 {
+public:
+  int fcn(int) { cout << "D2::fcn(int)" << endl; return 0; }
+  int fcn() { cout << "D2::fcn" << endl; return 0; }
+  void f2() { cout << "D2::f2" << endl; }
+};
+
+int main() {
+  Base bobj; D1 d1obj; D2 d2obj;
+  Base *bp1 = &bobj, *bp2 = &d1obj, *bp3 = &d2obj;
+  bp1->fcn(); // virtual call, will call Base::fcn at run time
+  bp2->fcn(); // virtual call, will call D1::fcn at run time  <--- changed
+  bp3->fcn(); // virtual call, will call D2::fcn at run time
+
+  return 0;
+}

ch15/15.24.md

@@ -0,0 +1 @@
+A base class usually needs a virtual destructor to allow objects in the inheritance hierarchy to be dynamically allocated. The virtual destructor must free dynamically alloacted resources in its class if so, otherwise, an empty virtual destructor is enough.

ch15/15.25.md

@@ -0,0 +1,3 @@
+Because if there exists any user-defined constructor, then there is no synthesized default constructor. And if we want to construct a default initialized `Bulk_quote` type object, all classes must have user-defined or synthesized default constructor in inheritance hierarchy. Thus we define a default constructor for `Disc_quote`.
+
+If we remove that constructor, the complier will not synthesized one for us, thus we could only create `Bulk_quote` object by providing arguments consistent with other constructors.

ch15/15.26.cpp

@@ -0,0 +1,206 @@
+// based on ex15.15
+#include <string>
+#include <iostream>
+
+class Quote {
+public:
+  Quote() {
+    std::cout << "Quote" << std::endl;
+  }
+
+  Quote(const std::string &book, double pri)
+      : bookNo(book), price(pri) {
+    std::cout << "Quote(const std::string &book, double pri)" << std::endl;
+  }
+
+  virtual ~Quote() {
+    std::cout << "~Quote" << std::endl;
+  }
+  Quote(const Quote &rhs) : price(rhs.price), bookNo(rhs.bookNo) {
+    std::cout << "Quote(const Quote &rhs)" << std::endl;
+  }
+  Quote(Quote &&rhs) : price(std::move(rhs.price)),
+                       bookNo(std::move(rhs.bookNo)) {
+    std::cout << "Quote(Quote &&rhs)" << std::endl;
+  }
+  Quote &operator=(const Quote &rhs) {
+    std::cout << "operator=(const Quote &rhs)" << std::endl;
+    price = rhs.price;
+    bookNo = rhs.bookNo;
+    return *this;
+  }
+  Quote &operator=(Quote &&rhs) {
+    std::cout << "operator=(Quote &&rhs)" << std::endl;
+    price = std::move(rhs.price);
+    bookNo = std::move(rhs.bookNo);
+    return *this;
+  }
+
+  std::string isbn() const { return bookNo; }
+  virtual double net_price(std::size_t n) const { return n * price; }
+
+  virtual std::ostream &debug(std::ostream &os) const {
+    os << "Quote::bookNo " << bookNo << " Quote::price " << price;
+    return os;
+  }
+
+protected:
+  double price = 0.0;
+
+private:
+  std::string bookNo;
+};
+
+class Disc_quote : public Quote {
+public:
+  Disc_quote() {
+    std::cout << "Disc_quote" << std::endl;
+  }
+  Disc_quote(const std::string &book, double pri,
+             std::size_t qty, double disc)
+      : Quote(book, pri), quantity(qty), discount(disc) {
+    std::cout << "Disc_quote(const std::string &book, ... )" << std::endl;
+  }
+
+  ~Disc_quote() {
+    std::cout << "~Disc_quote" << std::endl;
+  }
+  Disc_quote(const Disc_quote &rhs)
+      : Quote(rhs), quantity(rhs.quantity), discount(rhs.discount) {
+    std::cout << "Disc_quote(const Disc_quote &rhs)" << std::endl;
+  }
+  Disc_quote(Disc_quote &&rhs) : Quote(std::move(rhs)),
+                                 quantity(std::move(rhs.quantity)),
+                                 discount(std::move(rhs.discount)) {
+    std::cout << "Disc_quote(Disc_quote &&rhs)" << std::endl;
+  }
+  Disc_quote &operator=(const Disc_quote &rhs) {
+    Quote::operator=(rhs);
+    std::cout << "operator=(const Disc_quote &rhs)" << std::endl;
+    quantity = rhs.quantity;
+    discount = rhs.discount;
+    return *this;
+  }
+  Disc_quote &operator=(Disc_quote &&rhs) {
+    Quote::operator=(std::move(rhs));
+    std::cout << "operator=(Disc_quote &&rhs)" << std::endl;
+    quantity = std::move(rhs.quantity);
+    discount = std::move(rhs.discount);
+    return *this;
+  }
+
+  double net_price(std::size_t n) const = 0;
+
+  std::ostream &debug(std::ostream &os) const override {
+    Quote::debug(os) << " Disc_quote::quantity " << quantity
+        << " Disc_quote::discount " << discount;
+    return os;
+  }
+
+protected:
+  std::size_t quantity = 0;
+  double discount = 0.0;
+};
+
+class Bulk_quote : public Disc_quote {
+public:
+  Bulk_quote() = default;
+  Bulk_quote(const std::string &book, double pri, std::size_t qty, double disc)
+      : Disc_quote(book, pri, qty, disc) { }
+
+  double net_price(std::size_t n) const override {
+    if (n >= quantity)
+      return n * price * (1 - discount);
+    else
+      return n * price;
+  }
+};
+
+class Limit_quote : public Disc_quote {
+public:
+  Limit_quote() = default;
+  Limit_quote(const std::string &book, double pri, std::size_t qty, double disc)
+      : Disc_quote(book, pri, qty, disc) { }
+
+  double net_price(std::size_t n) const override {
+    if (n <= quantity)
+      return n * price * (1 - discount);
+    else
+      return (n - quantity) * price + quantity * price * (1 - discount);
+  }
+};
+
+double print_total(std::ostream &os, const Quote &item, size_t n) {
+  double ret = item.net_price(n);
+  os << "ISBN: " << item.isbn() << " # sold: " << n << " total due: " << ret
+     << std::endl;
+  return ret;
+}
+
+int main() {
+  Quote basic0;
+  basic0.debug(std::cout) << '\n' << std::endl;
+
+  Quote basic1("abc", 5.5);
+  basic1.debug(std::cout) << '\n' << std::endl;
+
+  Quote basic2(basic1);
+  basic2.debug(std::cout) << '\n' << std::endl;
+
+  Quote basic3(std::move(basic2));
+  basic3.debug(std::cout) << std::endl;
+  basic2.debug(std::cout) << '\n' << std::endl;
+
+  basic2 = basic3;
+  basic2.debug(std::cout) << '\n' << std::endl;
+
+  basic3 = std::move(basic1);
+  basic3.debug(std::cout) << std::endl;
+  basic1.debug(std::cout) << '\n' << std::endl;
+
+  std::cout << "============================" << std::endl; 
+
+  Bulk_quote bulk0;
+  bulk0.debug(std::cout) << '\n' << std::endl;
+
+  Bulk_quote bulk1("abc", 5.5, 10, 0.2);
+  bulk1.debug(std::cout) << '\n' << std::endl;
+
+  Bulk_quote bulk2(bulk1);
+  bulk2.debug(std::cout) << '\n' << std::endl;
+
+  Bulk_quote bulk3(std::move(bulk2));
+  bulk3.debug(std::cout) << std::endl;
+  bulk2.debug(std::cout) << '\n' << std::endl;
+
+  bulk2 = bulk3;
+  bulk2.debug(std::cout) << '\n' << std::endl;
+
+  bulk3 = std::move(bulk1);
+  bulk3.debug(std::cout) << std::endl;
+  bulk1.debug(std::cout) << '\n' << std::endl;
+
+  std::cout << "============================" << std::endl; 
+
+  Limit_quote limit0;
+  limit0.debug(std::cout) << '\n' << std::endl;
+
+  Limit_quote limit1("abc", 5.5, 5, 0.1);
+  limit1.debug(std::cout) << '\n' << std::endl;
+
+  Limit_quote limit2(limit1);
+  limit2.debug(std::cout) << '\n' << std::endl;
+
+  Limit_quote limit3(std::move(limit2));
+  limit3.debug(std::cout) << std::endl;
+  limit2.debug(std::cout) << '\n' << std::endl;
+
+  limit2 = limit3;
+  limit2.debug(std::cout) << '\n' << std::endl;
+
+  limit3 = std::move(limit1);
+  limit3.debug(std::cout) << std::endl;
+  limit1.debug(std::cout) << '\n' << std::endl;
+
+  return 0;
+}