Added Comment in Queue.cpp

Data Structures/Circular Linked List/C/circularlisnkedlist.c

@@ -0,0 +1,234 @@
+#include<stdio.h>
+#include<stdlib.h>
+
+struct node
+{
+  struct node *prev;
+  int info;
+  struct node *next;
+};
+
+struct node *start = NULL;
+
+struct node *createcdll(struct node *);
+struct node *printcdll(struct node *);
+struct node *inscdllfirst(struct node *);
+struct node *inscdllend(struct node *);
+struct node *delcdlfirst(struct node *);
+struct node *delcdlend(struct node *);
+struct node *inscdllafgn(struct node *);
+
+
+struct node *createcdll(struct node *start)
+{
+  struct node *new,*ptr;
+  int item;
+
+  printf("enter -1 to end circular linked list\n");
+  printf("enter the item you want\n");
+  scanf("%d",&item);
+  while (item!=-1)
+  {
+    new = (struct node* )malloc(sizeof(struct node));
+    new->info=item;
+
+    if(start==NULL)
+    {
+      start=new;
+      new->prev=start;
+      new->next=start;
+
+    }
+    else
+    {
+      ptr=start;
+      while(ptr->next!=start)
+      {
+        ptr=ptr->prev;
+      }
+      new->prev=ptr;
+      ptr->next=new;
+      new->next=start;
+      start->prev=new;
+    }
+    scanf("%d",&item);
+  }
+  return start;
+}
+
+  struct node *printcdll(struct node *start)
+  {
+    struct node *ptr;
+    ptr = start;
+    if(start==NULL)
+    {
+      printf("the linked list is empty\n");
+    }
+    else
+    {
+    do
+      {
+    printf("%d  ",ptr->info);
+    ptr=ptr->next;
+  }while(ptr!=start);
+    }
+    return start;
+  }
+
+  struct node *inscdllfirst(struct node *start)
+  {
+    struct node *new,*ptr;
+    int item;
+    printf("enter the the item\n");
+    scanf("%d",&item);
+
+    ptr=start;
+    new = (struct node*)malloc(sizeof(struct node));
+    new->info=item;
+    ptr=start->prev;
+    ptr->next=new;
+    new->prev=ptr;
+    new->next=start;
+    start->prev=new;
+    start=new;
+    start=printcdll(start);
+
+    return start;
+
+  }
+
+struct node *inscdllend(struct node *start)
+{
+  struct node *ptr,*new;
+  int item;
+
+  printf("ENTER THE ELEMENT\n");
+  scanf("%d",&item);
+
+  ptr=start;
+  new = (struct node*)malloc(sizeof(struct node *));
+  new->info=item;
+  while(ptr->next!=start)
+  {
+     ptr=ptr->next;
+  }
+  ptr->next=new;
+  new->next=start;
+  new->prev=ptr;
+  start=printcdll(start);
+
+return start;
+}
+
+struct node *delcdlfirst(struct node *start)
+{
+  struct node *ptr,*save;
+  save = start;
+  if(start==NULL)
+  {
+    printf("the linked list is empty");
+  }
+  else
+  {
+    ptr=start->prev;
+    ptr->next=start->next;
+    (start->next)->prev=ptr;
+    start->prev=NULL;
+    start=start->next;
+    free(save);
+   }
+     start=printcdll(start);
+     return start;
+}
+
+struct node *delcdlend(struct node *start)
+{
+  struct node *ptr;
+  ptr=start;
+	ptr=ptr->prev;
+	(ptr->prev)->next=start;
+	start->prev=ptr->prev;
+	free(ptr);
+	ptr=NULL;
+   start=printcdll(start);
+	return start;
+}
+
+struct node *inscdllafgn(struct node *start)
+{
+  struct node *ptr,*new;
+  int value,item;
+  printf("enter the value after which you want to enter the new element\n");
+  scanf("%d",&value);
+  printf("enter the new item");
+  scanf("%d",&item);
+  ptr=start;
+
+  new = (struct node*)malloc(sizeof(struct node));
+  new->info=item;
+   while(ptr->info!=value)
+   {
+     ptr=ptr->next;
+   }
+   new->next=ptr->next;
+   ptr->next=new;
+   new->prev=ptr;
+   ptr=new->next;
+   ptr->prev=new;
+   start=printcdll(start);
+ return start;
+
+}
+
+int main()
+{
+  	int choice,g,an,y;
+
+  do
+  {
+
+	printf("\nOptions:\n");
+	printf("1.create the list\n");
+  printf("2.print the list\n");
+  printf("3.to enter element in the bigning\n");
+  printf("4.to enter element in the end\n");
+  printf("5.to delete the first element in the linkedlist\n");
+  printf("6.to delete the last element in the linkedlist\n");
+  printf("7.to enter a ite after the value you want\n");
+  scanf("%d",&choice);
+
+  switch(choice)
+  {
+    case 1:
+    start = createcdll(start);
+    break;
+    case 2:
+    start = printcdll(start);
+    break;
+    break;
+    case 3:
+    start = inscdllfirst(start);
+    break;
+    case 4:
+    start = inscdllend(start);
+    break;
+    case 5:
+    start = delcdlfirst(start);
+    break;
+    case 6:
+    start = delcdlend(start);
+    break;
+    case 7:
+    start = inscdllafgn(start);
+    break;
+    default:
+    printf("ivalid input");
+
+  }
+  printf("\npress 0 if you want to exit\n");
+  printf("OR enter 9 to continue\n");
+  scanf("%d",&an);
+   }while(an!= 0);
+
+return 0;
+}

Data Structures/Queue/CPP/Queue.cpp

@@ -8,12 +8,14 @@ using namespace std;
 
 //SEFIRA KARINA
 
+//node is declared
 struct Node
 {
 	int number;
 	struct Node *next;
 } *head, * tail, *temp;
 
+//function to delete node
 void deleteNode()
 {
     Node *ptrNode;
@@ -30,6 +32,7 @@ void deleteNode()
     }
 }
 
+//function to print a node
 void printNode()
 {
 
@@ -43,6 +46,8 @@ void printNode()
 	cout<< endl;
 
 }
+
+//function to add a new node
 void addNode(int x)
 {
 	temp = new Node;
@@ -59,6 +64,7 @@ void addNode(int x)
 	}
 }
 
+//driver function
 int main(void)
 {
     head=tail=NULL;