未分类题

某发票（lnvoice）由抬头（Head）部分、正文部分和脚注（Foot）部分构成。现采用装饰（Decorator）模式实现打印发票的功能，得到如图5-1所示的类图。

【C++代码】
#include
using namespace std;
class Invoice{
public:
（1）{
cout＜＜"This is the content of the invoice!"＜＜endl;
}
};
class Decorator:public Invoice{
Invoice*ticket;
public:
Decorator(lnvoice*t){ticket=t;}
void printInvoice（　　）{
if(ticket!=NULL)
（2）;
}
};
class HeadDecorator:public Decorator{
public:
HeadDecorator(lnvoice*t):Decorator(t){}
void printInvoice（　　）{
cout＜＜"This is the header of the invoice!"＜＜endl;
（3）;
}
};
class FootDecorator:public Decorator{
public:
FootDecorator(Invoice*t):Decorator(t){}
void printlnvoice（　　）{
（4）;
cout＜＜"This is the footnote of the invoice!"＜＜endl;
}
};
int main(void){
Invoice t;
FootDecorator f(&t);
HeadDecorator h(&f);
h.printInvoice（　　）;
cout＜＜”------------------------”＜＜endl;
FootDecorator a(NULL);
HeadDecorator b(（5）);
b.printInvoice（　　）;
return 0;
}
程序的输出结果为：
This is the header of the invoice!
This is the content of the invoice!
This is the footnote of the invoice!
----------------------------
This is the header of the invoice!
This is the footnote of the invoice!