class screen
{
public:
void menu(void)
{
cout<<“\n\n\n\n **********************”;
cout<<“\n\t\t\t\t”<<“1.CREAT”<<endl<<“\t\t\t\t”<<“2.APPEND”
<<endl<<“\t\t\t\t”<<“3.DELETE”<<endl<<“\t\t\t\t”<<“4.DISPLAY”
<<endl<<“\t\t\t\t”<<“5.INSERT BEGGNING”<<endl<<“\t\t\t\t”<<“6.INSERT”
<<endl<<“\t\t\t\t”<<“7.MODIFY”<<endl<<“\t\t\t\t”<<“8.INVERSE DISPLAY”
<<endl<<“\t\t\t\t”<<“9.FIND”
<<endl<<“\t\t\t\t”<<“10.EXIT”;
cout<<“\n *******************”;
}
}s;

struct link_list
{
int info;
struct link_list *next;
struct link_list *pre;
};

typedef struct link_list link;

int count=0;

class ll
{
link *first,*list,*temp,*pointer;
public:
ll()
{
first=list;
}
int isempty(void);
void creat(void);
void append(void);
void del(void);
void insbeg(void);
void ins(void);
void modify(void);
void display(void);
void inv(void);
void find(int x);
};

int ll::isempty()
{
if(first==list)
return(1);
return(0);
}

void ll::creat()
{
if(first==list)
count=0;
else
count=1;
if(count!=0)
{
cout<<“\nTHE LIST ALREADY EXISTS!”;
getch();
return;
}
char ch;
list=new link;
first=list;
while(1)
{
cout<<“\nENTER INFO:”;
cout<<“\nDO U WANT TO CONTINUE:”;
cin>>ch;
if(ch==’n’)
break;
list->next=new link;
list->next->pre=list;
list=list->next;
}
list->next=first;
first->pre=list;
}

void ll::append()
{
if(first==list)
return;
list=first;
while(list->next!=first)
list=list->next;
list->next=new link;
list->next->pre=list;
list=list->next;
list->next=first;
cout<<“\nENTER INFO:”;
cin>>list->info;
}

void ll::insbeg()
{
if(first==list)
return;
temp=new link;
cout<<“\nENTER INFO:”;
cin>>temp->info;
temp->next=first;
temp->pre=first->pre;
first->pre->next=temp;
first->pre=temp;
first=temp;
}

void ll::ins()
{
if(first==list)
return;
list=first;
temp=new link;
int rec;
cout<<“\nENTER THE INFO AFTER WHICH NEW INFO IS TO BE INSERTED:”;
cin>>rec;
while(list->next!=first)
{
if(list->info==rec)
{
temp->next=list->next;
temp->pre=list;
list->next->pre=temp;
list->next=temp;
cout<<“\nENTER THE INFO:”;
cin>>temp->info;
list=list->next;
return;
}
list=list->next;
}
cout<<“\nRECORD NOT FOUND!”;
getch();
}

void ll::del()
{
// if(list==first)
// return;
list=first;
cout<<“\nENTER THE INFO WHICH IS TO BE DELETED:”;
int t;
cin>>t;
if(first->info==t)
{
first->next->pre=first->pre;
first->pre->next=first->next;
first=first->next;
return;
}
while(list->next->next!=first)
{
if(list->info==t)
{
list->next->pre=list->pre;
list->pre->next=list->next;
return;
}
list=list->next;
}
if(list->next->next==first)
{
if(list->next->info==t)
{
list->next=first;
first->pre=list;
return;
}
}

cout<<“\nRECORD NOT FOUND!”;
getch();

}

void ll::modify()
{
if(first==list)
return;
int t;
list=first;
temp=new link;
cout<<“\nENTER THE INFO TO BE MODIFIED:”;
cin>>temp->info;
if(first->info==temp->info)
{
cout<<“\nENTER NEW INFO:”;
cin>>t;
first->info=t;
delete temp;
return;
}

while(list->next!=first)
{
if(list->info==temp->info)
{
cout<<“\nENTER NEW INFO:”;
cin>>t;
list->info=t;
delete temp;
return;
}
list=list->next;
}
if(list->next==first)
{
if(list->info==temp->info)
{
cout<<“\nENTER INFO:”;
cin>>t;
list->info=t;
list=list->pre;
return;
}
}
cout<<“\nRECORD IS NOT IN THE LIST!”;
getch();
}

void ll::inv()
{
clrscr();
cout<<“\nTHE INVERTED LIST IS:”;
first=list;
while(first->pre!=list)
{
cout<<“\t”<<first->info;
first=first->pre;
}
cout<<“\t”<<first->info;
getch();
}

void ll::find(int x)
{
if(first==list)
return;
int count=1;
list=first;
if(first->info==x)
{
list=list->next;
cout<<“\nTHE RECORD FOUND IN POSITION:”<<count;
getch();
return;
}
while(list->next!=first)
{
if(list->info==x)
{
cout<<“\nTHE RECORD FOUND IN POSITION:”<<count;
getch();
return;
}
list=list->next;
count++;
}
if(list->next==first)
{
if(list->info==x)
{
cout<<“\nTHE RECORD FOUND IN POS:”<<count;
getch();
return;
}
}
cout<<“\nRECORD NOT FOUND!”;
getch();
}

void ll::display()
{
clrscr();
int a=isempty();
if(a==1)
{
cout<<” LIST EMPTY!”;
cout<<“Projeh List Halghavi-Taheye Konandeh”;
return;
}
list=first;
cout<<“\nTHE LINKED LIST IS:”;
while(list->next!=first)
{
cout<<“\t”<<list->info;
list=list->next;
}
cout<<“\t”<<list->info;
}

void main()
{
clrscr();
ll a;
int ch;
do
{
a.display();
s.menu();
cout<<“\nENTER CHOICE:”;
cin>>ch;
switch(ch)
{
case 1:a.creat();break;
case 2:a.append();break;
case 3:a.del();break;
case 4:a.display();break;
case 5:a.insbeg();break;
case 6:a.ins();break;
case 7:a.modify();break;
case 8:a.inv();break;
case 9:cout<<“ENTER THE INFO WHICH IS TO BE SEARCHED:”;
int x;
cin>>x;
a.find(x);
break;
case 10:break;
default:cout<<“TRY AGAIN!”;
getch();
}
}while(ch!=10);
getch();
}