circular linked list added

Data Structures/Linked List/C/circular linked list 2.c

@@ -0,0 +1,219 @@
+#include <stdio.h>
+#include <stdlib.h>
+typedef struct nodetype
+{
+    int data;
+    struct nodetype *next;
+}node;
+node* create_node()
+{
+    node *ptr;
+    ptr=(node *)malloc(sizeof(node));
+    printf("enter data\n");
+    scanf("%d",&(ptr->data));
+    ptr->next=NULL;
+    return ptr;
+}
+node* create_list(node *tl,int n)
+{
+    node *ptr; int i;
+    ptr=tl;
+    for(i=0;i<n;i++)
+    {
+        ptr->next=create_node();
+        ptr=ptr->next;
+    }
+    ptr->next=tl;
+    return ptr;
+}
+void display_list(node* tail)
+{
+    if(tail==NULL)
+    {
+        printf("EMPTY LIST");
+    }
+    else
+    {
+        node* curr;
+        curr=tail->next;
+        printf("Exsisting list:-");
+        while(curr!=tail)
+        {
+            printf("%d  ",curr->data);
+            curr=curr->next;
+        }
+        printf("%d\n",curr->data);
+    }
+}
+node* insert_end(node* tl)
+{
+    node *newnode,*ptr;
+    ptr=tl;
+    newnode=create_node();
+    newnode->next=ptr->next;
+    ptr->next=newnode;
+    return newnode;
+}
+void insert_front(node* tl)
+{
+    node *newnode,*ptr;
+    ptr=tl;
+    newnode=create_node();
+    newnode->next=ptr->next;
+    ptr->next=newnode;
+}
+void insert_mid(node* tl,int i)
+{
+    node* ptr;
+    node* prev;
+    node* newnode;int j;
+    ptr=tl->next;
+    for(j=1;j<i-1;j++)
+    {
+        ptr=ptr->next;
+    }
+    newnode=create_node();
+    newnode->next=ptr->next;
+    ptr->next=newnode;
+}
+node* del_end(node* tl)
+{
+    node *ptr,*newnode;
+    ptr=tl->next;
+    while(ptr->next!=tl)
+    {
+        ptr=ptr->next;
+    }
+    newnode=tl;
+    ptr->next=tl->next;
+    free(newnode);
+    return ptr;
+}
+void del_front(node* tl)
+{
+    node *ptr,*newnode;
+    ptr=tl->next;
+    newnode=ptr;
+    ptr=ptr->next;
+    tl->next=ptr;
+    free(newnode);
+}
+void del_mid(node* tl,int i)
+{
+    node* ptr;
+    node *prev;
+    int j;
+    ptr=tl;
+    for(j=0;j<i-1;j++)
+    {
+        prev=ptr;
+        ptr=ptr->next;
+    }
+    prev->next=ptr->next;
+    free(ptr);
+}
+int main()
+{
+    node* tail;
+    int n,c;
+    int pos;
+    tail=NULL;
+    while(c!=0)
+    {
+        printf("enter 1 to create list\n");
+        printf("enter 2 to display the list\n");
+        printf("enter 3 to append\n");
+        printf("enter 4 to insert at front\n");
+        printf("enter 5 to insert at the middle\n");
+        printf("enter 6 to delete at end\n");
+        printf("enter 7 to delete at front\n");
+        printf("enter 8 to delete at the middle\n");
+        printf("enter 9 to stop\n");
+        printf("enter your choice\n");
+        scanf("%d",&c);
+        switch(c)
+        {
+            case 1:
+            {
+                printf("enter number of elements of the list\n");
+                scanf("%d",&n);
+                tail=(node *)malloc(sizeof(node));
+                printf("enter data\n");
+                scanf("%d",&(tail->data));
+                tail->next=tail;
+                tail= create_list(tail,n-1);
+                break;
+            }
+            case 2:
+            {
+                display_list(tail);
+                break;
+            }
+            case 3:
+            {
+                tail= insert_end(tail);
+                n++;
+                break;
+            }
+            case 4:
+            {
+                insert_front(tail);
+                n++;
+                break;
+            }
+            case 5:
+            {
+                printf("enter your position\n");
+                scanf("%d",&pos);
+                if(pos>n+1 || pos<=0)
+                {
+                    printf("invalid position\n");
+                    continue;
+                }
+                else
+                {
+                    insert_mid(tail,pos);
+                    n++;
+                }
+                break;
+            }
+            case 6:
+            {
+                tail= del_end(tail);
+                n--;
+                break;
+            }
+            case 7:
+            {
+                del_front(tail);
+                n--;
+                break;
+            }
+            case 8:
+            {
+                printf("enter your position\n");
+                scanf("%d",&pos);
+                if(pos>n || pos<=0)
+                {
+                    printf("invalid position\n");
+                    continue;
+                }
+                else
+                {
+                    del_mid(tail,pos);
+                    n--;
+                }
+                break;
+            }
+            case 9:
+            {
+                exit(0);
+            }
+            default:
+            {
+                printf("wrong choice\n");
+                break;
+            }
+        }
+    }
+}