Added circular linked list

circularlinkedlist.c

@@ -0,0 +1,243 @@
+#include<stdio.h>  
+#include<stdlib.h>  
+struct node   
+{  
+    int data;  
+    struct node *next;   
+};  
+struct node *head;  
+
+void beginsert ();   
+void lastinsert ();  
+void randominsert();  
+void begin_delete();  
+void last_delete();  
+void random_delete();  
+void display();  
+void search();  
+void main ()  
+{  
+    int choice =0;  
+    while(choice != 7)   
+    {  
+        printf("\n*********Main Menu*********\n");  
+        printf("\nChoose one option from the following list ...\n");  
+        printf("\n===============================================\n");  
+        printf("\n1.Insert in begining\n2.Insert at last\n3.Delete from Beginning\n4.Delete from last\n5.Search for an element\n6.Show\n7.Exit\n");  
+        printf("\nEnter your choice?\n");         
+        scanf("\n%d",&choice);  
+        switch(choice)  
+        {  
+            case 1:  
+            beginsert();      
+            break;  
+            case 2:  
+            lastinsert();         
+            break;  
+            case 3:  
+            begin_delete();       
+            break;  
+            case 4:  
+            last_delete();        
+            break;  
+            case 5:  
+            search();         
+            break;  
+            case 6:  
+            display();        
+            break;  
+            case 7:  
+            exit(0);  
+            break;  
+            default:  
+            printf("Please enter valid choice..");  
+        }  
+    }  
+}  
+void beginsert()  
+{  
+    struct node *ptr,*temp;   
+    int item;   
+    ptr = (struct node *)malloc(sizeof(struct node));  
+    if(ptr == NULL)  
+    {  
+        printf("\nOVERFLOW");  
+    }  
+    else   
+    {  
+        printf("\nEnter the node data?");  
+        scanf("%d",&item);  
+        ptr -> data = item;  
+        if(head == NULL)  
+        {  
+            head = ptr;  
+            ptr -> next = head;  
+        }  
+        else   
+        {     
+            temp = head;  
+            while(temp->next != head)  
+                temp = temp->next;  
+            ptr->next = head;   
+            temp -> next = ptr;   
+            head = ptr;  
+        }   
+        printf("\nnode inserted\n");  
+    }  
+
+}  
+void lastinsert()  
+{  
+    struct node *ptr,*temp;   
+    int item;  
+    ptr = (struct node *)malloc(sizeof(struct node));  
+    if(ptr == NULL)  
+    {  
+        printf("\nOVERFLOW\n");  
+    }  
+    else  
+    {  
+        printf("\nEnter Data?");  
+        scanf("%d",&item);  
+        ptr->data = item;  
+        if(head == NULL)  
+        {  
+            head = ptr;  
+            ptr -> next = head;    
+        }  
+        else  
+        {  
+            temp = head;  
+            while(temp -> next != head)  
+            {  
+                temp = temp -> next;  
+            }  
+            temp -> next = ptr;   
+            ptr -> next = head;  
+        }  
+
+        printf("\nnode inserted\n");  
+    }  
+
+}  
+
+void begin_delete()  
+{  
+    struct node *ptr;   
+    if(head == NULL)  
+    {  
+        printf("\nUNDERFLOW");    
+    }  
+    else if(head->next == head)  
+    {  
+        head = NULL;  
+        free(head);  
+        printf("\nnode deleted\n");  
+    }  
+
+    else  
+    {   ptr = head;   
+        while(ptr -> next != head)  
+            ptr = ptr -> next;   
+        ptr->next = head->next;  
+        free(head);  
+        head = ptr->next;  
+        printf("\nnode deleted\n");  
+
+    }  
+}  
+void last_delete()  
+{  
+    struct node *ptr, *preptr;  
+    if(head==NULL)  
+    {  
+        printf("\nUNDERFLOW");  
+    }  
+    else if (head ->next == head)  
+    {  
+        head = NULL;  
+        free(head);  
+        printf("\nnode deleted\n");  
+
+    }  
+    else   
+    {  
+        ptr = head;  
+        while(ptr ->next != head)  
+        {  
+            preptr=ptr;  
+            ptr = ptr->next;  
+        }  
+        preptr->next = ptr -> next;  
+        free(ptr);  
+        printf("\nnode deleted\n");  
+
+    }  
+}  
+
+void search()  
+{  
+    struct node *ptr;  
+    int item,i=0,flag=1;  
+    ptr = head;   
+    if(ptr == NULL)  
+    {  
+        printf("\nEmpty List\n");  
+    }  
+    else  
+    {   
+        printf("\nEnter item which you want to search?\n");   
+        scanf("%d",&item);  
+        if(head ->data == item)  
+        {  
+        printf("item found at location %d",i+1);  
+        flag=0;  
+        }  
+        else   
+        {  
+        while (ptr->next != head)  
+        {  
+            if(ptr->data == item)  
+            {  
+                printf("item found at location %d ",i+1);  
+                flag=0;  
+                break;  
+            }   
+            else  
+            {  
+                flag=1;  
+            }  
+            i++;  
+            ptr = ptr -> next;  
+        }  
+        }  
+        if(flag != 0)  
+        {  
+            printf("Item not found\n");  
+        }  
+    }     
+
+}  
+
+void display()  
+{  
+    struct node *ptr;  
+    ptr=head;  
+    if(head == NULL)  
+    {  
+        printf("\nnothing to print");  
+    }     
+    else  
+    {  
+        printf("\n printing values ... \n");  
+
+        while(ptr -> next != head)  
+        {  
+
+            printf("%d\n", ptr -> data);  
+            ptr = ptr -> next;  
+        }  
+        printf("%d\n", ptr -> data);  
+    }  
+
+}