雖然還不是很懂啊，但卻很有意思。

下面把辛辛苦苦打的代碼貼出來，大家一起學習。

下面是 Picture.h ：

#include<iostream>
using namespace std;
class P_Node{
 friend class Picture;

protected:
 P_Node();
 virtual ~P_Node();
 virtual int height() const=0;
 virtual int width() const=0;
 virtual void display
  (ostream&,int,int)const=0;
 //int max(int,int);
private:
 int use;
};

class Picture{
 friend ostream& operator<<(ostream&,const Picture&);
 friend Picture frame(const Picture&);
 friend Picture operator&(const Picture&,const Picture&);
 friend Picture operator|(const Picture&,const Picture&);
 friend class String_Pic;
 friend class Frame_Pic;
 friend class Hcat_Pic;
 friend class VCat_Pic;

public:
 Picture();
 Picture(const char* const*,int);
 Picture(const Picture&);
 ~Picture();
 
 Picture& operator=(const Picture&);
private:
 Picture(P_Node*);
 int height() const;
 int width() const;
 void display(ostream&,int,int) const;
 P_Node* p;
};

class String_Pic:public P_Node{
 friend class Picture;
 String_Pic(const char* const*,int);
 ~String_Pic();
 int height() const;
 int width() const;
 void display(ostream&,int,int) const;
 char** data;
 int size;
};

class Frame_Pic:public P_Node{
 friend Picture frame(const Picture&);
 Frame_Pic(const Picture&);
 int height() const;
 int width() const;
 void display(ostream&,int,int) const;
 Picture p;
};

class VCat_Pic:public P_Node{
 friend Picture operator&
  (const Picture&,const Picture&);
 VCat_Pic(const Picture&,const Picture&);
 int height() const;
 int width() const;
 void display(ostream&,int,int) const;
 Picture top,bottom;
};

class Hcat_Pic:public P_Node{
 friend Picture operator|
  (const Picture&,const Picture&);
 Hcat_Pic(const Picture&,const Picture&);
 int height() const;
 int width() const;
 void display(ostream&,int,int) const;
 Picture left,right;
};

下面是 Picture.cpp ：

#include"Picture.h"
#include<iostream>
#include<cstring>
using namespace std;

P_Node::~P_Node(){}
P_Node::P_Node():use(1){}

static void pad(ostream& os,int x,int y)
{
 for(int i=x;i<y;i++)
  os<<" ";
}
int max(int x,int y)
{
 return x>y?x:y;
}

Picture::Picture(const char* const* str,int n):
 p(new String_Pic(str,n)){}

Picture::Picture(const Picture& orig):p(orig.p)
{
 orig.p->use++;
};

Picture::Picture(P_Node* p_node):p(p_node){}

Picture::~Picture()
{
 if(--p->use==0)
  delete p;
}

Picture& Picture::operator=(const Picture& orig)
{
 orig.p->use++;
 if(--p->use==0)
  delete p;
 p=orig.p;
 return *this;
}

int Picture::height() const
{
 return p->height();
}

int Picture::width() const
{
 return p->width();
}

void Picture::display(ostream& o,int x,int y)const
{
 p->display(o,x,y);
}

ostream& operator<<(ostream& os,const Picture& picture)
{
 int ht=picture.height();
 for(int i=0;i<ht;i++){
  picture.display(os,i,0);
  os<<endl;
 }
 return os;
}

String_Pic::String_Pic(const char* const* p,int n):
 data(new char* [n]),size(n)
{
 for(int i=0;i<n;i++){
  data[i]=new char[strlen(p[i])+1];
  strcpy(data[i],p[i]);
 }
}

int String_Pic::height() const
{
 return size;
}

int String_Pic::width() const
{
 int n=0;
 for(int i=0;i<size;i++){
  n=max(n,strlen(data[i]));
 }
 return n;
}

void String_Pic::display(ostream& os,int row,int width)const
{
 int start=0;
 if(row>=0&&row<height()){
  os<<data[row];
  start=strlen(data[row]);
 }
 pad(os,start,width);
}

String_Pic::~String_Pic()
{
 for(int i=0;i<size;i++)
  delete[] data[i];
 delete[] data;
}

Frame_Pic::Frame_Pic(const Picture& pic):p(pic){}
int Frame_Pic::height()const
{
 return p.height()+2;
}
int Frame_Pic::width()const
{
 return p.width()+2;
}

void Frame_Pic::display(ostream& os,int row,int wd)const
{
 if(row<0||row>=height()){
  pad(os,0,wd);
 }else{
  if(row==0||row==height()-1){
   os<<"+";
   int i=p.width();
   while(--i>=0)
    os<<"-";
   os<<"+";
  }else{
   os<<"|";
   p.display(os,row-1,p.width());
   os<<"|";
  }
  pad(os,width(),wd);
 }
}

Picture frame(const Picture& pic)
{
 return new Frame_Pic(pic);
}

VCat_Pic::VCat_Pic(const Picture& t,const Picture& b):
 top(t),bottom(b){}

int VCat_Pic::height()const
{
 return top.height()+bottom.height();
}
int VCat_Pic::width()const
{
 return max(top.width(),bottom.width());
}
void VCat_Pic::display(ostream& os,int row,int wd)const
{
 if(row>=0 && row< top.height())
  top.display(os,row,wd);
 else if(row <top.height()+bottom.height())
  bottom.display(os,row-top.height(),wd);
 else
  pad(os,0,wd);
}
Picture operator&(const Picture& t,const Picture& b)
{
 return new VCat_Pic(t,b);
}

Hcat_Pic::Hcat_Pic(const Picture& l,const Picture& r):
 left(l),right(r){}

int Hcat_Pic::height()const
{
 return max(left.height(),right.height());
}
int Hcat_Pic::width()const
{
 return left.width()+right.width();
}
void Hcat_Pic::display(ostream& os,int row,int wd)const
{
 left.display(os,row,left.width());
 right.display(os,row,right.width());
 pad(os,width(),wd);
}

Picture operator|(const Picture& l,const Picture& r)
{
 return new Hcat_Pic(l,r);
}

下面是 test.cpp ：

#include<iostream>
#include<cstring>
#include"Picture.h"

using namespace std;

char *init[]={"Paris","in the","Spring"};
int main()
{
 Picture p(init,3);
 cout<<p<<endl;

 Picture q=frame(p);
 cout<<q<<endl;

 cout<<(q&(p|q))<<endl;

 cout<<frame(p|p)<<endl;

 cout<<frame(q|q)<<endl;

 cout<<(p&p)<<endl;

 cout<<(q&q)<<endl;

 cout<<frame(p&p)<<endl;
 cout<<frame(frame(q&q)|frame(p&p))<<endl;
 return 0;
}