Program of singly link list

# include <iostream.h>
# include <process.h>
# include <conio.h>
# include <malloc.h>

int cur_link_list=1;
int display_menu();
struct link_list
{
 int no;
 struct link_list *next;
};

class link
{
 link_list *list;
 public:
       link_list *head;
       link()
       {
    list=NULL;
    head=NULL;
       }
       void get_list();
       void display_list();
       void insert();
       void delete_list();
       void sort();
       void merge(link_list *,link_list*);
       friend void union_list(link_list *,link_list *);
       friend void intersact(link_list *,link_list *);
       void reverse();
};

void link :: get_list()
{
  int no;
  list=head;
  while(list->next!=NULL)
  {
   list=list->next;
  }
  while(1)
  {
    cout<<\"Enter Number :\";
    cin>>no;
    if(no!=0)
    {
      if(list==NULL)
      {
       list=new link_list;
       head=list;
      }





      list->no=no;
      list->next = new link_list;
      list=list->next;
    }
    else
    {
     list->next=NULL;
     break;
    }
  }
}

void link :: display_list()
{
 list=head;
 cout<<endl;
 if (list==NULL)
 {
  cout<<\"Link list is empty !!!\";
  return;
 }
 while(list->next!=NULL)
 {
   cout<<list->no<<\"\\t\";
   list=list->next;
 }
}

void link :: insert()
{
  int ch;
  list=head;
  cout<<endl;
  cout<<\"[ 1 ] : Insert at First\"<<endl;
  cout<<\"[ 2 ] : Insert in Middle\"<<endl;
  cout<<\"[ 3 ] : Insert at Last\"<<endl;
  cout<<\"[ 4 ] : Back to main Menu\"<<endl;
  cout<<\"Enter your choice :\";
  cin>>ch;
  link_list *newnode;
  newnode=new link_list;
  switch(ch)
  {
   case 1:
       cout<<\"Enter Number :\";
       cin>>newnode->no;
       list=head;
       if(list==NULL)
       {
        list=newnode;
        newnode->next=NULL;
        head=list;
       }
       else
       {
        newnode->next=list;
        head=newnode;
       }
       break;
   case 2: int no;
       cout<<endl;
       cout<<\"Enter Number after which you want to insert :\";
       cin>>no;
       list=head;






       while(list->next !=NULL)
       {
         if(list->no==no)
         {
           cout<<\"Enter Number to Insert :\";
           cin>>newnode->no;
           newnode->next=list->next;
           list->next=newnode;
           if(list==head)
           {
         head=newnode;
           }
           return;
         }
         list=list->next;
       }
       cout<<\"Key not found ...\"<<endl;
       break;
   case 3 : list=head;
        while(list->next!=NULL)
        {
         list=list->next;
        }
        cout<<\"Enter Number :\";
        cin>>newnode->no;

        if(head==NULL)
        {
         list=newnode;
         head=list;
        }
        else
        {
         list->next=newnode;
         newnode->next=NULL;
        }
        break;
  }
}

void link :: delete_list()
{
 cout<<endl;
 list=head;
 int no;
 cout<<\"Enter the number to deleted :\";
 cin>>no;
  if(head->no==no)
   {
    head=head->next;
    return;
   }

 while(list->next!=NULL)
 {
   if(list->next->no==no)
   {
     list->next=list->next->next;
     return;
   }
   list=list->next;
 }
 cout<<\"Number not not found !!!\";
}






void link :: sort()
{
 link_list *i,*j,*t;
 for(i=head;i->next!=NULL;i=i->next)
 {
  for(j=head;j->next!=NULL;j=j->next)
  {
   if(i->no < j->no)
   {
     t->no=i->no;
     i->no=j->no;
     j->no=t->no;
   }
  }
 }
}

void union_list(link_list *l1,link_list *l2)
{
  cout<<endl;
  link_list *h;
  h=l1;

  while(l1->next!=NULL)
  {
    cout<<l1->no<<\"\\t\";
    l1=l1->next;
  }
 int flag=0;
  while(l2->next!=NULL)
  {
     l1=h;
     flag=0;
     while(l1->next!=NULL)
     {
      if(l1->no==l2->no)
      {
       flag=1;
       break;
      }
      l1=l1->next;
     }
     if(flag==0)
     {
       cout<<l2->no<<\"\\t\";
     }
     l2=l2->next;
  }
}
void intersact (link_list *l1,link_list *l2)
{
 link_list *h;
 h=l2;
 while(l1->next!=NULL)
 {
   l2=h;
   while(l2->next!=NULL)
   {
     if(l1->no==l2->no)
     {
      cout<<l1->no<<\"\\t\";
      break;
     }
     l2=l2->next;
   }





   l1=l1->next;
 }
}

void link :: reverse()
{
 int a[50];
 list=head;
 int i=0;
 while(list->next!=NULL)
 {
  a[i]=list->no;
  list=list->next;
  i=i+1;
 }
 int n=i-1;
 i=n;
 list=head;
 while(list->next!=NULL)
 {
  list->no=a[i];
  list=list->next;
  i=i-1;
 }
}

void link :: merge(link_list *l1,link_list *l2)
{
 head=NULL;
 list=new link_list;
 while(l1->next !=NULL)
 {
   if(head==NULL)
   {
    head=list;
   }
   list->no=l1->no;
   list->next=new link_list;
   list=list->next;
   l1=l1->next;
 }
 while(l2->next !=NULL)
 {
  list->no=l2->no;
  list->next=new link_list;
  list=list->next;
  list->next=NULL;
  l2=l2->next;
 }
 list->next=NULL;
}
void main()
{
 clrscr();
 link l1,l2,l3;
 while(1)
 {
  switch(display_menu())
  {
      case 1: cout<<\"Enter LinkList Number [ 1 , 2 , 3 ]:\";
          int n;
          cin>>n;
          if(n>=1 && n<=3)
          {
           cur_link_list=n;





          }
          break;
      case 2: switch(cur_link_list)
          {
           case 1: l1.get_list();
               break;
           case 2: l2.get_list();
               break;
           case 3: l3.get_list();
               break;
          }
          getch();
          break;

      case 3: switch(cur_link_list)
          {
        case 1 : l1.insert();
             break;
        case 2 : l2.insert();
             break;
        case 3 : l3.insert();
             break;
          }
          getch();
          break;
      case 4: switch(cur_link_list)
          {
        case 1: l1.display_list();
            break;
        case 2: l2.display_list();
            break;
        case 3: l3.display_list();
            break;
          }
          getch();
          break;
      case 5:
          switch(cur_link_list)
          {
           case 1: l1.display_list();
               l1.delete_list();
               break;

           case 2: l2.display_list();
               l2.delete_list();
               break;

           case 3: l3.display_list();
               l3.delete_list();
               break;
          }

          getch();
          break;
      case 6: cout<<endl;
          switch(cur_link_list)
          {
        case 1: l1.sort();
            l1.display_list();
            break;
        case 2: l2.sort();
            l2.display_list();
            break;
        case 3: l3.sort();
            l3.display_list();





            break;
          }
          cout<<endl<<endl<<\"Linklist sorted !!!\";
          getch();
          break;

      case 7: cout<<endl<<endl<<\"Union of First two List...\"<<endl;
          union_list(l1.head,l2.head);
          getch();
          break;
      case 8:cout<<endl<<endl<<\"Intersaction of First two list...\"<<endl;
         intersact(l1.head,l2.head);
         getch();
         break;
      case 9: switch(cur_link_list)
          {
           case 1: l1.reverse();
               break;
           case 2: l2.reverse();
               break;
           case 3: l3.reverse();
               break;
          }
          getch();
          break;
      case 10 : l3.merge(l1.head,l2.head);
        cout<<endl;
        cout<<\"First two linklist merged in third link list !!!\";
        l3.display_list();
        getch();
        break;
      case 11 : exit(1);

  }
 }

}

int display_menu()
{
 clrscr();
 cout<<endl;
 cout<<\" [ 01 ] Select Linklist (Selected List is:\"<<cur_link_list<<\")\"<<endl;
 cout<<\" [ 02 ] Get Elements\"<<endl;
 cout<<\" [ 03 ] Insert\"<<endl;
 cout<<\" [ 04 ] Display\"<<endl;
 cout<<\" [ 05 ] Delete\"<<endl;
 cout<<\" [ 06 ] Sort\"<<endl;
 cout<<\" [ 07 ] Union\"<<endl;
 cout<<\" [ 08 ] Intersaction\"<<endl;
 cout<<\" [ 09 ] Reverse\"<<endl;
 cout<<\" [ 10 ] Merge Linklist\"<<endl;
 cout<<\" [ 11 ] Exit\"<<endl;
 cout<<\" Enter your choice :\";
 int ch;
 cin>>ch;
 return ch;
}