Linked list operations implemented in C.

linkedlistOperations.c

#include<stdio.h>
#include<stdlib.h>
struct Node
{
    int data;
    struct Node* link;
};
struct Node* header = NULL;

int getSize()
{
    int size = 0;
    struct Node* ptr = header;
    while(ptr != NULL)
    {
        size++;
        ptr = ptr->link;
    }
    return size;
}

void display()
{
    struct Node* ptr = header;
    // int count = 1;
    if(header == NULL)
    {
        printf("\nEmpty!\n");
        exit(1);
    }
    else
    {
        printf("\nElements are:\n");
        while(ptr != NULL)
        {
            // printf("\nData at node %d is %d", count, ptr->data);
            printf("%d\t", ptr->data);
            ptr = ptr->link;
            // count++;
        }
        printf("\nThere are %d elements.\n", getSize());
    }
}

void insertAtFront(int el)
{
    struct Node* temp = ((struct Node*)malloc(sizeof(struct Node)));
    if(temp == NULL)
    {
        printf("\nNot enough memory!");
        exit(1);
    }
   	temp->data = el;
    temp->link = header;
    header = temp;
    display();
}

void insertAtRear(int el)
{
    if(header == NULL)
    {
    	insertAtFront(el);
    	return;
    }
    struct Node* new_ptr = (struct Node*)malloc(sizeof(struct Node));
    new_ptr->data = el;
    new_ptr->link = NULL;
    struct Node* ptr = header;
    while(ptr->link != NULL)
    {
    	ptr = ptr->link;
    }
    ptr->link = new_ptr;
	display();
}

void insertAtAny(int el, int pos)
{
    if((pos > getSize()) && (pos != getSize() + 1))
    {
        printf("\nCannot insert an element at position %d", pos);
        return;
    }
	struct Node* new_ptr = (struct Node*)malloc(sizeof(struct Node));
	new_ptr->data = el;
	new_ptr->link = NULL;
    struct Node* ptr = header;
    int i = 2;
    if(pos == 1)
    {
    	new_ptr->link = header;
    	header = new_ptr;
    	display();
    	return;
    }
    while(ptr != NULL && i != pos)
    {
    	ptr = ptr->link;
    	i++;
    }
    new_ptr->link = ptr->link;
    ptr->link = new_ptr;
    display();
}

void deleteAtFront()
{
	struct Node* ptr = header;
	 //struct Node* temp;
	if(ptr == NULL)
	{
		printf("\nList is empty!");
		exit(1);
	}
	/* temp = ptr->link;
	header->link = temp; */
	header = header->link;
	free(ptr);
    display();
}

void deleteAtRear()
{
    struct Node* ptr = header;
    struct Node* temp;
    if(ptr->link == NULL)
    {
    	printf("\nList is empty!\n");
    	exit(1);
    }
    while(ptr->link != NULL)
    {
    	temp = ptr;
    	ptr = ptr->link;
    }
    temp->link = NULL;
    free(ptr);
    display();
}

void deleteAtAny(int data)
{
    struct Node* ptr;
    struct Node* temp;
    temp = header;
    ptr = temp->link;
    while(ptr != NULL)
    {
        if(ptr->data != data)
        {
          temp = ptr;
    	  ptr = ptr->link;
        }
        else
        {
          temp->link = ptr->link;
          free(ptr);
          display();
          return;

        }
    }
    if(ptr == NULL)
    {
        printf("\nNode with data %d not found within the list!", data);
    }
    display();
}
/* void deleteAtAny(int pos)
{
    if(pos > getSize())
    {
        printf("\nInvalid position!");
        return;
    }
    struct Node* ptr;
    struct Node* temp;
    int i = 2;
    temp = header;
    ptr = temp->link;
    if(pos == 1)
    {
    	deleteAtFront();
    	return;
    }
    while(ptr->link != NULL && i != pos)
    {
    	temp = ptr;
    	ptr = ptr->link;
    	i++;
	}
	temp->link = ptr->link;
    free(ptr);
	display();
} */

int main()
{
    char choice, cont;
    int el, pos, data;
    do{
        printf("\n1.Insert at front\n2.Insert at rear\n3.Insert at any position\n4.Delete at front\n5.Delete at rear\n6.Delete at any position\n7.Display\nEnter your option: ");
        scanf("%c", &choice);
        switch(choice)
        {
            case '1':
                printf("\nElement to be inserted: ");
                scanf("%d", &el);
                insertAtFront(el);
                break;
            case '2':
                printf("\nElement to be inserted: ");
                scanf("%d", &el);
                insertAtRear(el);
                break;
            case '3':
                printf("\nElement to be inserted: ");
                scanf("%d", &el);
                printf("\nPosition to be inserted: ");
                scanf("%d", &pos);
                insertAtAny(el, pos);
                break;
            case '4':
                deleteAtFront();
                break;
            case '5':
                deleteAtRear();
                break;
            case '6':
            	printf("\nData of the node to be deleted: ");
            	scanf("%d", &data);
                deleteAtAny(data);
                break;
            case '7':
                display();
                break;
            default:
                printf("\nInvalid option!");
        }
        printf("\nWant to continue? ");
        scanf("%c", &cont);
    }while(1);
    return 0;
}