doubly link list

#include<stdio.h>
#include<stdlib.h>
typedef struct node
{
    int a;
    char s[20];
    struct node *next;
    struct node *prev;
}node;
node *head=NULL,*tail=NULL;
void displaylst()           //Display last To First.
{  int ch;
    node *list=tail;
    if(head==NULL)
    {
        printf("NO Data Available!!\n\n ");
    }
    else
    {
    while(list!=NULL)
    {
         printf("Name: %s\n",list->s);
        printf("Age: %d\n\n",list->a);
        list=list->prev;
    }
    }
    printf("         1.Menu\n");
    printf("         2.Exit\n");
    printf("Press Any Option:");
    scanf("%d",&ch);
     switch(ch)
    {
    case 1:
        {
            menu();
        }
    case 2:
        {
            exit(0);
        }

    default:
        {

             printf("You Choose Wrong Option!!\a\n\n");
            menu();
            break;
        }

}
}

void displayfrst()    //Display First To Last.
{  int ch;
    node *list=head;
     if(head==NULL)
    {
        printf("             NO Data Available!!\n\n ");
    }
    else
    {
    while(list!=NULL)
    {
         printf("Name: %s\n",list->s);
        printf("Age: %d\n\n",list->a);
        list=list->next;
    }
    }
      printf("         1.Menu\n");
    printf("         2.Exit\n");
    printf("Press Any Option:");
    scanf("%d",&ch);
    switch(ch)
    {
    case 1:
        {
            menu();
        }
    case 2:
        {
            exit(0);
        }

    default:
        {

             printf("You Choose Wrong Option!!\a\n\n");
            menu();
            break;
        }

}
}

void display()   //Choose Display Type.
{
    int ch,n;
    printf("       1.Display 1st To Last\n");
    printf("       2.Display Last To 1st\n");
    printf("Choose Any Option:");
    scanf("%d",&n);
    switch(n)
    {
    case 1:
        {
            displayfrst();
            break;
        }
    case 2:
        {
            displaylst();
            break;
        }
    default:
        {
              printf("You Choose Wrong Option!!\a\n\n");
            menu();
            break;
        }
    }
}
void searchpos()  //Search By Position.
{
    int ch,n;
    node *list=head;
    printf("Enter Your Position:");
    scanf("%d",&n);
    if(n==1)
    {
        printf("Name: %s\n",list->s);
        printf("Age: %d\n\n",list->a);
    }
    else
    {   n=n-2;
        while(n!=0&&list->next!=NULL)
        {
            list=list->next;
            n--;
        }
        if(list->next==NULL)
        {
            printf("No Information Available!!\n\n");
        }
        else
        {
             printf("Name: %s\n",list->next->s);
        printf("Age: %d\n\n",list->next->a);
        }
    }
    printf("         1.Menu\n");
    printf("         2.Exit\n");
    printf("Press Any Option:");
    scanf("%d",&ch);
    switch(ch)
    {
    case 1:
        {
            menu();
        }
    case 2:
        {
            exit(0);
        }

    default:
        {

             printf("You Choose Wrong Option!!\a\n\n");
            menu();
            break;
        }

}
}

void searchval()  //Search By Value.
{  node *list=head;
    int ch,v;
    printf("Enter Your Age:");
    scanf("%d",&v);
    if(list->a==v)
    {
        printf("Name: %s\n",list->s);
        printf("Age: %d\n\n",list->a);
    }
    else
    {
        while(list->next->a!=v&&list!=0)
        {
            list=list->next;
        }
        if(list==NULL)
        {
            printf("No Information Available!!\n\n");
        }
        else
        {
             printf("Name: %s\n",list->next->s);
        printf("Age: %d\n\n",list->next->a);
        }
    }
    printf("           1.Menu\n");
    printf("           2.Exit\n");
    printf("Press Any Option:");
    scanf("%d",&ch);
    switch(ch)
    {
    case 1:
        {
            menu();
        }
    case 2:
        {
            exit(0);
        }

    default:
        {

             printf("You Choose Wrong Option!!\a\n\n");
            menu();
            break;
        }

}
}

void search()  //Choose Search Type.
{   int ch;
    printf("        1.Search By Value\n");
    printf("        2.Search By Position\n");
    printf("Choose Any Option:");
    scanf("%d",&ch);
    switch(ch)
    {
    case 1:
        {
            searchval();
            break;
        }
    case 2:
        {
            searchpos();
            break;
        }
    default :
        {
            printf("You Choose Wrong Option!!\n");
            menu();
            break;

        }
    }
}

void deletepos()  //Delete By Position.
{
     int n,ch;
    node *list=head,*temp;
    printf("please enter position:");
    scanf("%d",&n);
    if(n==1)
    {
        head=list->next;
        head->prev=NULL;
        free(list);
    }
    else{

        n=n-2;
        while(n!=0&&list->next!=NULL)
        {
            list=list->next;
            n--;
        }
        if(list->next->next==NULL&&n==0)
        {     temp=tail;
            tail=tail->prev;
                tail->next=NULL;
             free(temp);
             printf("              Block No: %d is Deleted!!\n\n",n);
        }
        else if(list->next==NULL)
        {
            printf("           You Choose Wrong Position!!\a\n\n");
        }
        else
        {
            temp=list->next;
            temp->next->prev=list;
            list->next=temp->next;
            free(temp);
             printf("              Block No: %d is Deleted!!\n\n",n);
        }
    }
     printf("           1.Menu\n");
    printf("              2.Exit\n");
    printf("Press Any Option:");
    scanf("%d",&ch);
    switch(ch)
    {
    case 1:
        {
            menu();
        }
    case 2:
        {
            exit(0);
        }

    default:
        {

             printf("You Choose Wrong Option!!\a\n\n");
            menu();
            break;
        }

}

}

void deleteval() //Delete By Value.
{   int n,ch;
    node *list=head,*temp;
    printf("please enter age:");
    scanf("%d",&n);
    if(head==NULL)
    {
        printf("No Information Available!!\n\n");
    }
  else if(list->a==n&&list->next==NULL)
    {
        head=NULL;
        tail=NULL;
        free(list);
         printf("             Data Deleted!!\n\n");
    }
    else if(list->a==n)
    {
        temp=list;
        list=list->next;
        list->prev=NULL;
        head=list;
        free(temp);
         printf("             Data Deleted!!\n\n");
    }
    else
    {
        while((list->next->a!=n)&&(list->next!=NULL))
        {
            list=list->next;
        }
        if(list->next==NULL)
        {
            printf("No Value Available\n");
        }
        else if(list->next->a==n&&list->next->next==NULL)
        {
            temp=tail;
            tail=tail->prev;
             free(temp);
            tail->next=NULL;

            printf("             Data Deleted!!\n\n");
        }
        else
        {
            temp=list->next;
            list->next=temp->next;
            temp->next->prev=list;
            free(temp);
             printf("            Data Deleted!!\n\n");
        }
    }
    printf("           1.Menu\n");
    printf("           2.Exit\n");
    printf("Press Any Option:");
    scanf("%d",&ch);
    switch(ch)
    {
    case 1:
        {
            menu();
        }
    case 2:
        {
            exit(0);
        }

    default:
        {

             printf("You Choose Wrong Option!!\a\n\n");
            menu();
            break;
        }

}

}

void Delete()  //Choose Deleting Type.
{  int ch,n;
   printf("         1.Delete By Value\n");
   printf("         2.Delete By Position\n");
   printf("Choose Any Option:");
   scanf("%d",&ch);
   switch(ch)
   {
   case 1:
    {
        deleteval();
        break;
    }
    case 2:
    {
        deletepos();
        break;
    }
    default:
        {
             printf("You Choose Wrong Option!!\a\n\n");
            menu();
            break;
        }
   }

}

void addpos()   //Add By Position.
{
    int p,ch;
    node *list=head;
     node *n=(node*)malloc(sizeof(node));
n->prev=NULL;
    n->next=NULL;
    printf("\nName:");
       scanf(" %s[^\n]",n->s);
       printf("Age:");
       scanf("%d",&n->a);
       printf("Enter Your Position:");
       scanf("%d",&p);
       if(p==1)
       {
            head->prev=n;
           n->next=head;
           head=n;
       }
       else
       {
           p=p-2;
           while(p!=0&&list->next!=NULL)
           {
               list=list->next;
               p--;
           }
           if(list->next==NULL)
           {
               tail->next=n;
               n->prev=tail;
               tail=n;
           }
           else
           {
           n->next=list->next;
           list->next->prev=n;
           n->prev=list;

           list->next=n;
           }
       }
          printf("           1.Menu\n");
    printf("                 2.Exit\n");
    printf("Press any Option:");
    scanf("%d",&ch);
    switch(ch)
    {
    case 1:
        {
            menu();
        }
    case 2:
        {
            exit(0);
        }

    default:
        {

             printf("You Choose Wrong Option!!\a\n\n");
            menu();
            break;
        }
    }

}


void addlast() //Add At Last.
{
     int ch;
    node *n=(node*)malloc(sizeof(node));
n->prev=NULL;
    n->next=NULL;
    printf("\nName:");
       scanf(" %s[^\n]",n->s);
       printf("Age:");
       scanf("%d",&n->a);

    if(head==NULL&&tail==NULL)
    {
        head=n;
        tail=n;
    }
    else
    {
        tail->next=n;
        n->prev=tail;
        tail=n;
    }
       printf("        1.Menu\n");
    printf("            2.Exit\n");
      printf("Press any Option:");
    scanf("%d",&ch);
    switch(ch)
    {
    case 1:
        {
            menu();
        }
    case 2:
        {
            exit(0);
        }

    default:
        {

             printf("You Choose Wrong Option!!\a\n\n");
            menu();
            break;
        }
}
}


void addfirst() //Add At First.
{   int ch;
    node *n=(node*)malloc(sizeof(node));
n->prev=NULL;
    n->next=NULL;
printf("\nName:");
       scanf(" %s[^\n]",n->s);
       printf("Age:");
       scanf("%d",&n->a);

    if(head==NULL&&tail==NULL)
    {
        head=n;
        tail=n;
    }
    else
    {
           head->prev=n;
           n->next=head;
           head=n;
    }

    printf("        1.Menu\n");
    printf("        2.Exit\n");
      printf("Press any Option:");
    scanf("%d",&ch);
    switch(ch)
    {
    case 1:
        {
            menu();
        }
    case 2:
        {
            exit(0);
        }

    default:
        {

             printf("You Choose Wrong Option!!\a\n\n");
            menu();
            break;
        }
}
}
void add() //Choose Add Type.
{int ch;
     printf("              1.Add At First\n");
     printf("              2.Add At Last\n");
     printf("              3.Add By position\n");
     printf("Choose any Option:");
     scanf("%d",&ch);
     switch(ch)
     {
     case 1:
        {
            addfirst();
            break;
        }
     case 2:
        {
            addlast();
            break;
        }
     case 3:
        {
            addpos();
            break;
        }
        default:
        {
             printf("You Choose Wrong Option!!\a\n\n");
            menu();
            break;
        }
     }
}
void menu() //Menu bar.
{int n;

      printf("\n\n");
    printf("                                                 1.Add");
    printf("             2.Search\n");
    printf("                                                        3.Delete\n");
    printf("                                              4.Display");
    printf("              5.Exit\n");
    printf("Choose any Option:");
    scanf("%d",&n);
    switch(n)
    {
    case 1:
        {
            add();
            break;
        }
    case 2:
        {
            search();
            break;
        }
    case 3:
        {
            Delete();
            break;
        }
    case 4:
        {
            display();
            break;
        }
    case 5:
        {
            exit(0);
            break;
        }
        default:
        {
            printf("You Choose Wrong Option!!\a\n\n");
            menu();
            break;
        }
    }
}

int main()
{   printf("   DOUBLY LINK LIST\n");
printf(" ______________________\n");
    menu();
    return 0;
}