Header linked list in C

Author: Deepali-Srivastava

linked-list/single-linked-list-header-node.c

@@ -0,0 +1,214 @@
+/*
+Copyright (C) Deepali Srivastava - All Rights Reserved
+This code is part of DSA course available on CourseGalaxy.com    
+*/
+
+#include<stdio.h>
+#include<stdlib.h>
+
+struct node
+{
+	int info;
+	struct node *link;
+};
+
+void createList(struct node *head);
+void displayList(struct node *head);
+void insertAtEnd(struct node *head,int data);
+void insertBefore(struct node *head,int data,int x);
+void insertAtPosition(struct node *head,int data,int k);
+void deleteNode(struct node *head,int data);
+void reverse(struct node *head);
+
+main()
+{
+	int choice,data,x,k;
+	struct node *head;	
+	
+	head=(struct node *)malloc(sizeof(struct node));
+	head->info=0;	
+	head->link=NULL;
+	
+	createList(head);
+	
+	while(1)
+	{
+		printf("1.Display list\n");
+		printf("2.Insert a node at the end of the list\n");
+		printf("3.Insert a new node before a node\n");
+		printf("4.Insert at a given position\n");
+		printf("5.Delete a node\n");
+		printf("6.Reverse the list\n");
+		printf("7.Quit\n\n");
+		printf("Enter your choice : ");
+		scanf("%d",&choice);
+		
+		if(choice==7)
+			break;
+
+		switch(choice)
+		{
+		 case 1:
+			displayList(head);
+			break;
+		 case 2:
+			printf("Enter the element to be inserted : ");
+			scanf("%d",&data);
+			insertAtEnd(head,data);
+			break;
+		 case 3:
+			printf("Enter the element to be inserted : ");
+			scanf("%d",&data);
+			printf("Enter the element before which to insert : ");
+			scanf("%d",&x);
+			insertBefore(head,data,x);
+			break;
+		 case 4:
+			printf("Enter the element to be inserted : ");
+			scanf("%d",&data);
+			printf("Enter the position at which to insert : ");
+			scanf("%d",&k);
+			insertAtPosition(head,data,k);
+			break;
+		 case 5:
+			printf("Enter the element to be deleted : ");
+			scanf("%d",&data);
+			deleteNode(head,data);	
+			break;
+		 case 6:
+			reverse(head);
+			break;
+		 default:
+			printf("Wrong choice\n\n");
+		}
+	}/*End of while */
+}/*End of main()*/
+
+void displayList(struct node *head)
+{
+	struct node *p;
+	if(head->link==NULL)
+	{
+		printf("List is empty\n");
+		return;
+	}
+	p=head->link;
+	printf("List is :\n");
+	while(p!=NULL)
+	{
+		printf("%d ",p->info);
+		p=p->link;
+	}
+	printf("\n");
+}/*End of displayList()*/
+
+void insertAtEnd(struct node *head,int data)
+{
+	struct node *p,*temp;
+	temp= (struct node *)malloc(sizeof(struct node));
+	temp->info=data;
+
+	p=head;
+	while(p->link!=NULL)
+		p=p->link;
+	
+	p->link=temp;
+	temp->link=NULL;
+}/*End of insertAtEnd()*/
+
+void createList(struct node *head)
+{
+	int i,n,data;
+
+	printf("Enter the number of nodes : ");
+	scanf("%d",&n);
+	
+	for(i=1; i<=n; i++)
+	{
+		printf("Enter the element to be inserted : ");
+		scanf("%d",&data);
+		insertAtEnd(head,data);	
+	}
+}/*End of createList()*/
+
+void insertBefore(struct node *head,int data,int x)
+{
+	struct node *temp,*p;
+	
+	/*Find pointer to predecessor of node containing x*/
+	p=head;
+	while(p->link!=NULL)
+	{
+		if(p->link->info==x)
+			break;
+		p=p->link;
+	}
+	
+	if(p->link==NULL)
+		printf("%d not present in the list\n",x);
+	else
+	{
+		temp=(struct node *)malloc(sizeof(struct node));
+		temp->info=data;
+		temp->link=p->link;
+		p->link=temp;
+	}
+}/*End of insertBefore()*/		
+
+void insertAtPosition(struct node *head,int data,int k)
+{
+	struct node *temp,*p;
+	int i;
+	
+	p=head;
+	for(i=1; i<=k-1 && p!=NULL; i++)
+		p=p->link;
+	
+	if(p==NULL)
+		printf("You can insert only upto %dth position\n\n",i-1);
+	else
+	{
+		temp=(struct node *)malloc(sizeof(struct node));
+		temp->info=data;
+		temp->link=p->link;
+		p->link=temp;
+	}	
+}/*End of insertAtPosition()*/
+
+void deleteNode(struct node *head, int data)
+{
+	struct node *temp,*p;
+
+	p=head;
+	while(p->link!=NULL)
+	{
+		if(p->link->info==data)   
+			break;
+		p=p->link;
+	}
+
+	if(p->link==NULL)
+		printf("Element %d not found\n",data);
+	else
+	{
+		temp=p->link;
+		p->link=temp->link;
+		free(temp);
+	}
+}/*End of deleteNode()*/
+
+void reverse(struct node *head)
+{
+	struct node *prev, *ptr, *next;
+	prev=NULL;
+	ptr=head->link;
+	while(ptr!=NULL)
+	{
+		next=ptr->link;
+		ptr->link=prev;
+		prev=ptr;
+		ptr=next;
+	}
+	head->link=prev;
+}/*End of reverse()*/
+