Program to illustrate the implementation of linked list as a Queue

 # include <iostream.h>
 # include <graphics.h>
 # include <stdlib.h>
 # include <conio.h>
 # include <dos.h>

 # define INSERT 0
 # define DELETE 1

 # define NORMAL 0
 # define WARNING 1

 class Linked_list_Queue
    {
       private:
        char fill_pattern[8];

        int inserted_element_count;

        struct node
            {
               long data;
               node *next;
            };

        node *rear;
        node *entry;
        node *print;
        node *front;

       public:
        Linked_list_Queue( );

        long get_element( );

        void Delete( );
        void Insert( );
        void print_linked_list( );
        void show_working( );
        void show_main_screen( );
        void waiting_for_input( );
        void show_element_screen(int);
        void clear_element_screen(int);
        void show_linked_list_screen( );
        void show_output_screen(int);
        void show_window(int,int,int,int);
    };


 /**************************************************************************/
 //----------------------  Linked_list_Queue( )  --------------------------//
 /**************************************************************************/

 Linked_list_Queue::Linked_list_Queue ( )
    {
       rear=NULL;
       front=NULL;
       inserted_element_count=0;

       fill_pattern[0]=0xAA;
       fill_pattern[1]=0x55;
       fill_pattern[2]=0xAA;
       fill_pattern[3]=0x55;
       fill_pattern[4]=0xAA;
       fill_pattern[5]=0x55;
       fill_pattern[6]=0xAA;
       fill_pattern[7]=0x55;
    }

 /**************************************************************************/
 //--------------------  show_window(int,int,int,int)  --------------------//
 /**************************************************************************/

 void Linked_list_Queue::show_window(int x_1,int y_1,int x_2,int y_2)
    {
       setcolor(15);
     rectangle(x_1,y_1,x_2,y_2);
     rectangle(x_1+1,y_1+1,x_2-1,y_2-1);

       setcolor(7);
     rectangle(x_1+2,y_1+2,x_2-2,y_2-2);
     rectangle(x_1+3,y_1+3,x_2-3,y_2-3);
     rectangle(x_1+4,y_1+4,x_2-4,y_2-4);

       setcolor(8);
     rectangle(x_1+5,y_1+5,x_2-5,y_2-5);
     rectangle(x_1+6,y_1+6,x_2-6,y_2-6);
     rectangle(x_1+7,y_1+7,x_2-7,y_2-7);
    }

 /**************************************************************************/
 //----------------------  show_main_screen( )  ---------------------------//
 /**************************************************************************/

 void Linked_list_Queue ::show_main_screen( )
    {
       setcolor(15);
       setlinestyle(1,0,3);
     rectangle(5,5,getmaxx( )-5,getmaxy( )-5);

       setlinestyle(0,0,0);

       show_window(5,5,getmaxx( )-5,80);

       setfillpattern(fill_pattern,4);
     bar(13,13,getmaxx( )-13,72);

       settextstyle(3,0,4);
     setcolor(0);
       outtextxy(17,22,\"Implementation of Linked List as Queue\");
       outtextxy(18,22,\"Implementation of Linked List as Queue\");

     setcolor(14);
       outtextxy(19,20,\"Implementation of Linked List as Queue\");
       outtextxy(20,20,\"Implementation of Linked List as Queue\");
       outtextxy(21,20,\"Implementation of Linked List as Queue\");

       show_window(5,82,305,getmaxy( )-5);

       setfillpattern(fill_pattern,9);
     bar(14,91,296,getmaxy( )-14);

       setcolor(6);
       setfillstyle(1,6);
     pieslice(215,105,0,360,10);

       setcolor(2);
       setfillstyle(1,2);
     pieslice(245,105,0,360,10);

       setcolor(4);
       setfillstyle(1,4);
     pieslice(275,105,0,360,10);

       setcolor(7);
     circle(215,105,11);
     circle(245,105,11);
     circle(275,105,11);

       show_window(307,82,getmaxx( )-5,getmaxy( )-5);

       settextstyle(7,0,4);
     setcolor(0);
       outtextxy(16,111,\"Press:\");

     setcolor(10);
       outtextxy(17,110,\"Press:\");
       outtextxy(18,110,\"Press:\");

       settextstyle(2,0,6);
     setcolor(0);
       outtextxy(59,151,\"<I> to Insert an Element\");
       outtextxy(59,171,\"<D> to Delete an Element\");
       outtextxy(59,191,\"<E> to Exit\");

     setcolor(14);
       outtextxy(60,150,\"<I> to Insert an Element\");
       outtextxy(61,150,\"<I> to Insert an Element\");

       outtextxy(60,170,\"<D> to Delete an Element\");
       outtextxy(61,170,\"<D> to Delete an Element\");

       outtextxy(60,190,\"<E> to Exit\");
       outtextxy(61,190,\"<E> to Exit\");

       setfillstyle(2,1);
     bar(317,92,getmaxx( )-15,getmaxy( )-15);
    }

 /**************************************************************************/
 //---------------------  show_linked_list_screen( )  ---------------------//
 /**************************************************************************/

 void Linked_list_Queue::show_linked_list_screen( )
    {
       for(int count=0;count<=187;count++)
      {
         setfillstyle(1,0);
           bar(317,280,getmaxx( )-15,278-count);
           bar(317,280,getmaxx( )-15,278+count);

         delay(5);
      }

       setcolor(12);
       settextstyle(2,0,7);
     outtextxy(405,400,\"Linked List (Queue)\");
     outtextxy(406,400,\"Linked List (Queue)\");
     outtextxy(407,400,\"Linked List (Queue)\");

       setfillstyle(1,6);
     bar(402,420,618,422);

       setcolor(15);
       setlinestyle(0,0,3);
     rectangle(330,405,390,435);

       setfillstyle(1,9);
     bar(331,406,374,434);

       setfillstyle(1,1);
     bar(376,406,389,434);

     line(375,405,375,435);

       setcolor(7);
       setlinestyle(0,0,0);
     line(352,425,352,455);  /* Entry->Data pointing arrow */
     line(352,455,415,455);

     line(412,452,415,455);
     line(412,458,415,455);

     line(382,423,382,443);   /* Entry->Next pointing arrow */
     line(382,443,415,443);

     line(412,440,415,443);
     line(412,446,415,443);

       setfillstyle(1,15);
     pieslice(382,420,0,360,2);

       settextstyle(0,0,1);
     setcolor(15);
       outtextxy(320,402,\"*\");

     setcolor(9);
       outtextxy(420,452,\"Entry->Data\");
       outtextxy(420,438,\"Entry->Next (x=NULL)\");

     setcolor(11);
       outtextxy(333,417,\"00000\");
    }

 /**************************************************************************/
 //-----------------------  show_output_screen(int)  ----------------------//
 /**************************************************************************/

 void Linked_list_Queue::show_output_screen(int NORMAL_WARNING)
    {
       int x_1;
       int x_2;
       int y_1;
       int y_2;

       if(NORMAL_WARNING==NORMAL)
      {
         x_1=20;
         x_2=280;
         y_1=277;
         y_2=350;
      }

       if(NORMAL_WARNING==WARNING)
      {
         x_1=20;
         x_2=280;
         y_1=277;
         y_2=367;
      }

       setcolor(15);
       setlinestyle(1,0,3);
     rectangle(x_1,y_1,x_2,y_2);

       setlinestyle(0,0,0);

       setcolor(15);
     rectangle(x_1,y_1,x_2,y_2);

       setcolor(7);
     rectangle(x_1+1,y_1+1,x_2-1,y_2-1);

       setcolor(8);
     rectangle(x_1+2,y_1+2,x_2-2,y_2-2);

       setfillstyle(1,9);
     bar(x_1+3,y_1+3,x_2-3,y_2-3);
    }

 /**************************************************************************/
 //----------------------  show_element_screen(int)  ----------------------//
 /**************************************************************************/

 void Linked_list_Queue::show_element_screen(int INSERT_DELETE)
    {
       show_output_screen(NORMAL);

       if(INSERT_DELETE==INSERT)
      {
         settextstyle(2,0,6);
           setcolor(0);
         outtextxy(28,281,\"Enter the Element :\");

           setcolor(11);
         outtextxy(29,280,\"Enter the Element :\");
         outtextxy(30,280,\"Enter the Element :\");
      }

       else if(INSERT_DELETE==DELETE)
      {
         settextstyle(2,0,6);
           setcolor(0);
         outtextxy(28,281,\"Deleted Element is :\");

           setcolor(11);
         outtextxy(29,280,\"Deleted Element is :\");
         outtextxy(30,280,\"Deleted Element is :\");
      }

       delay(300);

       for(int count=1;count<=65;count++)
      {
         setcolor(0);
         setfillstyle(1,0);
           bar(180-count,306,180+count,330);

           pieslice(180-count,318,0,360,12);
           pieslice(180+count,318,0,360,12);

         setcolor(15);
           line(180-count,302,180+count,302);
           line(180-count,334,180+count,334);

           arc(180-count,318,90,270,16);
           arc(180+count,318,270,90,16);

         setcolor(7);
           arc(180-count,318,90,270,15);
           arc(180-count,318,90,270,14);

           line(180-count,303,180+count,303);
           line(180-count,304,180+count,304);

           line(180-count,333,180+count,333);
           line(180-count,332,180+count,332);

           arc(180+count,318,270,90,15);
           arc(180+count,318,270,90,14);

         setcolor(8);
           line(180-count,305,180+count,305);
           line(180-count,331,180+count,331);

           arc(180-count,318,90,270,13);
           arc(180+count,318,270,90,13);

         delay(4);
      }
    }

 /**************************************************************************/
 //-------------------  clear_element_screen(int)  ------------------------//
 /**************************************************************************/

 void Linked_list_Queue::clear_element_screen(int NORMAL_WARNING)
    {
       if(NORMAL_WARNING==WARNING)
     {
         for(int count=1;count<=50;count++)
        {
           setfillpattern(fill_pattern,9);
             bar(18,275,290,275+count);
             bar(18,375,290,375-count);

           delay(20);
        }
      }

       else if(NORMAL_WARNING==NORMAL)
      {
         for(int count=1;count<=40;count++)
        {
           setfillpattern(fill_pattern,9);
             bar(18,275,290,275+count);
             bar(18,355,290,355-count);

           delay(20);
        }
      }
    }

 /**************************************************************************/
 //----------------------------  get_element( )  --------------------------//
 /**************************************************************************/

 long Linked_list_Queue::get_element( )
    {
       show_element_screen(INSERT);

       int count=0;
       char string[6]={\'\\0\'};

       do
      {
         int key_code=0;

         char key=NULL;

         if(kbhit( ))
        key=getch( );

         key_code=int(key);

         if(key_code>=48 && key_code<=57)
        {
           string[count]=key;
           count++;
        }

         else if(key_code==8 && count>0)
        {
           setfillstyle(1,0);
             bar(130,306,230,330);

           count--;
           string[count]=\'\\0\';
        }

         else if(key_code==13 && count>0)
        break;

         setcolor(12);
         settextstyle(2,0,7);

           moveto(140,305);
         outtext(string);

           moveto(141,305);
         outtext(string);

         int x=getx( );
         int y=305;

         while(!kbhit( ))
        {
           settextstyle(2,0,7);
             setcolor(12);
               moveto(x+2,y);
             outtext(\"_\");

           delay(250);

             setcolor(0);
               moveto(x+2,y);
             outtext(\"_\");

           delay(200);
           }
      }
       while(count<5);

       if(count==5)
      while(int(getch( ))!=13);

       long element=atol(string);

       clear_element_screen(NORMAL);

       return element;
    }

 /**************************************************************************/
 //-----------------------------  Insert( )  ------------------------------//
 /**************************************************************************/

 void Linked_list_Queue::Insert( )
    {
       long num=get_element( );

       for(int count=1;count<5;count++)
      {
         setcolor(0);
         setfillstyle(1,0);
           pieslice(215,105,0,360,10);

         delay(250);

         setcolor(6);
         setfillstyle(1,6);
           pieslice(215,105,0,360,10);

         delay(300);
      }

       if(inserted_element_count<15)
      {
         setcolor(10);
         setfillstyle(1,10);
           pieslice(245,105,0,360,10);

         sound(1500);
         delay(800);
         nosound( );

         setcolor(2);
         setfillstyle(1,2);
           pieslice(245,105,0,360,10);
      }

       if(inserted_element_count==15)
      {
         setcolor(12);
         setfillstyle(1,12);
           pieslice(275,105,0,360,10);

         sound(2500);
         delay(1000);
         nosound( );

         setcolor(4);
         setfillstyle(1,4);
           pieslice(275,105,0,360,10);

         delay(200);
      }

       entry=new(node);

       if(inserted_element_count==15)
      {
         show_output_screen(WARNING);

         settextstyle(7,0,4);
           setcolor(0);
         outtextxy(25,277,\"Error:\");
         outtextxy(26,277,\"Error:\");

           setcolor(14);
         outtextxy(27,275,\"Error:\");
         outtextxy(28,275,\"Error:\");

         while(!kbhit( ))
        {
           settextstyle(2,0,8);
             setcolor(0);
               outtextxy(46,309,\"Not enough heap\");
               outtextxy(47,309,\"Not enough heap\");

               outtextxy(28,335,\"space on Screen.\");
               outtextxy(29,335,\"space on Screen.\");

             setcolor(12);
               outtextxy(48,308,\"Not enough heap\");
               outtextxy(49,308,\"Not enough heap\");
               outtextxy(50,308,\"Not enough heap\");

               outtextxy(30,334,\"space on Screen.\");
               outtextxy(31,334,\"space on Screen.\");
               outtextxy(32,334,\"space on Screen.\");

           delay(500);

           setfillstyle(1,9);
             bar(23,315,277,362);

           delay(400);
        }

         getch( );
         clear_element_screen(1);
      }

       else if(rear==NULL)
      {
         entry->data=num;
         entry->next=NULL;
         rear=entry;
         front=rear;
         inserted_element_count++;
      }

       else
      {
         entry->data=num;
         entry->next=NULL;
         rear->next=entry;
         rear=entry;
         inserted_element_count++;
      }

       print_linked_list( );
    }

 /**************************************************************************/
 //---------------------------  Delete( )  --------------------------------//
 /**************************************************************************/

 void Linked_list_Queue::Delete( )
    {
       for(int count=1;count<5;count++)
      {
         setcolor(0);
         setfillstyle(1,0);
           pieslice(215,105,0,360,10);

         delay(250);

         setcolor(6);
         setfillstyle(1,6);
           pieslice(215,105,0,360,10);

         delay(300);
      }

       if(inserted_element_count==0)
      {
         setcolor(12);
         setfillstyle(1,12);
           pieslice(275,105,0,360,10);

         sound(2500);
         delay(1000);
         nosound( );

         setcolor(4);
         setfillstyle(1,4);
           pieslice(275,105,0,360,10);

         delay(200);
      }

       else if(inserted_element_count>0)
      {
         setcolor(10);
         setfillstyle(1,10);
           pieslice(245,105,0,360,10);

         sound(3000);
         delay(800);
         nosound( );

         setcolor(2);
         setfillstyle(1,2);
           pieslice(245,105,0,360,10);
      }

       if(front==NULL)
      {
         show_output_screen(WARNING);

         settextstyle(7,0,4);
           setcolor(0);
         outtextxy(25,277,\"Error:\");
         outtextxy(26,277,\"Error:\");

           setcolor(14);
         outtextxy(27,275,\"Error:\");
         outtextxy(28,275,\"Error:\");

         while(!kbhit( ))
        {
           settextstyle(6,0,4);
             setcolor(0);
               outtextxy(48,306,\"Nothing to Delete\");
               outtextxy(49,306,\"Nothing to Delete\");

             setcolor(12);
               outtextxy(50,305,\"Nothing to Delete\");
               outtextxy(51,305,\"Nothing to Delete\");
               outtextxy(52,305,\"Nothing to Delete\");

           delay(500);

           setfillstyle(1,9);
             bar(23,315,277,350);

           delay(400);
        }
         getch( );
      }

       else
      {
         long Deleted_element=front->data;

         node *temp;

         temp=front;
         front=front->next;
         inserted_element_count--;

         delete (temp);

         char element[6]={\'\\0\'};

         ltoa(Deleted_element,element,10);

         show_element_screen(DELETE);

         setcolor(12);
         settextstyle(2,0,7);
           outtextxy(140,305,element);
           outtextxy(141,305,element);

         delay(2500);
      }

       clear_element_screen(DELETE);
       print_linked_list( );
    }

 /**************************************************************************/
 //-----------------------  print_linked_list( )  -------------------------//
 /**************************************************************************/

 void Linked_list_Queue::print_linked_list( )
    {
       int count=0;
       int x=340;
       int y=100;

       print=front;

       setfillstyle(1,0);
     bar(317,92,getmaxx( )-15,getmaxy( )-80);

       while(print!=NULL)
      {
         setcolor(15);
         setlinestyle(0,0,3);
           rectangle(x,y,x+60,y+30);

         char element[6]={\'\\0\'};

         ltoa(print->data,element,10);

         if(count==0 || count==1 || count==2 || count==6 || count==7 ||
                 count==8 || count==12 || count==13 || count==14)
        {
           setfillstyle(1,9);
             bar(x+1,y+1,x+44,y+29);

           setfillstyle(1,1);
             bar(x+46,y+1,x+59,y+29);

           setcolor(15);
             line(x+45,y,x+45,y+30);

           setcolor(11);
           settextstyle(0,0,1);
             outtextxy(x+3,y+10,element);

           if(count==inserted_element_count-1)
              {
             setcolor(15);
             outtextxy(x+50,y+11,\"x\");
              }
        }

         else
        {
           setfillstyle(1,9);
             bar(x+16,y+1,x+59,y+29);

           setfillstyle(1,1);
             bar(x+1,y+1,x+14,y+29);

           setcolor(15);
             line(x+15,y,x+15,y+30);

           setcolor(11);
           settextstyle(0,0,1);
             outtextxy(x+18,y+10,element);

           if(count==inserted_element_count-1)
              {
             setcolor(15);
             outtextxy(x+4,y+11,\"x\");
              }
        }

         if(count==1 || count==2 || count==7 || count==8 || count==13
                                || count==14)
        {
           setcolor(15);
             line(x-45,y+15,x,y+15);

           setfillstyle(1,15);
             pieslice(x-47,y+15,0,360,2);

             line(x-6,y+11,x-2,y+15);
             line(x-6,y+19,x-2,y+15);
        }

         else if(count==4 || count==5 || count==10 || count==11)
        {
           setcolor(15);
             line(x+60,y+15,x+105,y+15);

           setfillstyle(1,15);
             pieslice(x+107,y+15,0,360,2);

             line(x+66,y+11,x+62,y+15);
             line(x+66,y+19,x+62,y+15);
        }

         else if(count==3 || count==9)
        {
           setcolor(15);
             setfillstyle(1,15);
               pieslice(x+53,y-45,0,360,2);

             setlinestyle(0,0,3);
               line(x+55,y-45,x+75,y-45);
               line(x+75,y-45,x+75,y+15);
               line(x+60,y+15,x+75,y+15);

               line(x+62,y+15,x+66,y+11);
               line(x+62,y+15,x+66,y+19);
        }

         else if(count==6 || count==12)
        {
           setcolor(15);
             setfillstyle(1,15);
               pieslice(x+7,y-45,0,360,2);

             setlinestyle(0,0,3);
               line(x-15,y-45,x+10,y-45);
               line(x-15,y-45,x-15,y+15);
               line(x-15,y+15,x,y+15);

               line(x-2,y+15,x-6,y+11);
               line(x-2,y+15,x-6,y+19);
        }

         setcolor(7);
         setlinestyle(0,0,3);
           line(350,125,350,138);  /* Bottom Arrow */
           line(346,134,350,138);
           line(354,134,350,138);

         setcolor(14);
         settextstyle(2,0,4);
           outtextxy(332,140,\"Front\");

         if(count==inserted_element_count-1)
        {
           setcolor(7);
           setlinestyle(0,0,3);
            line(x+30,y+25,x+30,y+38);
            line(x+26,y+34,x+30,y+38);
            line(x+34,y+34,x+30,y+38);

           setcolor(14);
           settextstyle(2,0,4);
             outtextxy(x+30,y+40,\"Rear\");
        }

         print=print->next;
         count++;

         if(count==0 || count==1 || count==2 || count==6 || count==7 ||
                 count==8 || count==12 || count==13 || count==14)
        x+=100;

         else if(count==3 || count==4 || count==5 || count==9 ||
             count==10 ||  count==11)
        x-=100;

         if(count==3 || count==9)
        {
           x=540;
           y+=60;
        }

         else if(count==6 || count==12)
        {
           x=340;
           y+=60;
        }

          if(count==15)
         break;
      }

       setlinestyle(0,0,0);
    }

 /**************************************************************************/
 //------------------------  waiting_for_input( )  ------------------------//
 /**************************************************************************/

 void Linked_list_Queue ::waiting_for_input( )
    {
       do
      {
         setfillstyle(1,4);
           bar(51,440,99,445);

         setfillstyle(1,10);
           bar(101,440,149,445);

         setfillstyle(1,1);
           bar(151,440,199,445);

         setfillstyle(1,14);
           bar(201,440,249,445);

         delay(300);

         setfillpattern(fill_pattern,9);
           bar(51,440,99,445);

         delay(150);

           bar(101,440,149,445);

         delay(150);

           bar(151,440,199,445);

         delay(150);

           bar(201,440,249,445);

         delay(150);

         setfillstyle(1,4);
           bar(51,440,99,445);

         delay(150);

         setfillstyle(1,10);
           bar(101,440,149,445);

         delay(150);

         setfillstyle(1,1);
           bar(151,440,199,445);

         delay(150);

         setfillstyle(1,14);
           bar(201,440,249,445);
      }
       while(!kbhit( ));

       setfillpattern(fill_pattern,9);
     bar(51,440,249,445);
    }

 /**************************************************************************/
 //---------------------------  show_working( )  --------------------------//
 /**************************************************************************/

 void Linked_list_Queue ::show_working( )
    {
       show_main_screen( );
       delay(1000);
       show_linked_list_screen( );

       char ch;

       do
      {
         waiting_for_input( );
         ch=getch( );

         switch(ch)
        {
           case \'i\': Insert( );
                 break;

           case \'I\': Insert( );
                 break;

           case \'d\': Delete( );
                 break;

           case \'D\': Delete( );
                 break;

           case \'e\': delay(500);
                 exit(0);

           case \'E\': delay(500);
                 exit(0);
        }
      }
       while(int(ch)!=27);

       delay(500);
    }



 main( )
    {
       int driver=VGA;
       int mode=VGAHI;

       initgraph(&driver,&mode,\"..\\\\Bgi\");

       Linked_list_Queue  obj;

       obj.show_working( );

       closegraph( );

       return 0;
    }