類的繼承-複製控制-虛函數–0822

//C++ primer plus ...... chapter 15  page490#include <iostream>#include <string>#include <new>#include <functional>using namespace std;#if 1//base classclass Item_base{public://constructor and destructorItem_base(const string & book = "" , double sales_price=0.0):isbn(book),price(sales_price){}virtual ~Item_base() {}//common interfacestring get_isbn() const { return isbn; }double get_price() const {return price ;}virtual double net_price(size_t n) const {cout << "Item_base." << __func__ << endl;return n*price;}private:string isbn;protected:double price;};//derived classclass Bulk_item : public Item_base {public://constructorBulk_item(const string & str, double prc , size_t qty=5 , double discnt=0.2): Item_base(str, prc) ,min_qty(qty),discount(discnt) { }double net_price(size_t) const;private:size_t min_qty; //minimum quantity for discountdouble discount; };double Bulk_item::net_price(size_t cnt) const{cout << "Bulk_item." << __func__ << endl;if(cnt >= min_qty)return cnt*(1 - discount)*price;elsereturn cnt*price;}void print_books(ostream &os, const Item_base & item , size_t n){os << "ISBN : " << item.get_isbn()<< "\tprice : " << item.get_price()<< "\tnumber :" << n << "\ttotal price : " << item.net_price(n)<< endl << endl; }int main(int argc, char const *argv[]){double book_price = 2.99;//base class objectItem_base book1("book1", book_price);//derived class objectBulk_item book2("boot2", book_price , 10, 0.1);Item_base &ref_1 = book1;print_books(cout , ref_1, 10);//copy control , derived to base, ref_1 = book2;print_books(cout , ref_1, 100);Item_base &ref_2 = book2;print_books(cout , ref_2, 100);return 0;}#endif
//makefile
TARGET= aaaCC= gccCXX= g++INCLUDES=LIBS=CFLAGS= -Wall -WerrorLINKFLAGS=C_SOURCES= $(wildcard *.c)C_OBJS= $(patsubst %.c, %.o, $(C_SOURCES))CPP_SOURCES= $(wildcard *.cpp)CPP_OBJS= $(patsubst %.cpp, %.o, $(CPP_SOURCES)).c.o:$(CC) -c -o $*.o $(CFLAGS) $(INCLUDES) $*.c.cpp.o:$(CXX) -c -o $*.o $(CFLAGS) $(INCLUDES) $*.cppcompile: $(CPP_OBJS) $(C_OBJS)$(CXX) $(LINKFLAGS) -o $(TARGET) $^ $(LIBS)clean:rm -f $(CPP_OBJS) $(C_OBJS)rm -f $(TARGET)uninstall:rm -f $(TARGET)rebuild: clean compile