singly_linked_list

#include<stdio.h>
#include<stdlib.h>

struct Node
{
    int data;
    struct Node *next;
};

struct Node *head = NULL;

void CreatAList(int n)
{
    for(int i=0; i<n; i++)
    {
        int val;
        scanf("%d",&val);
        struct Node *newNode = (struct Node*) malloc(sizeof(struct Node));
        newNode -> data = val;
        newNode -> next = NULL;
        if(head == NULL)
        {
            head = newNode;
        }
        else
        {
            struct Node *cur;
            cur = head;
            while(cur -> next != NULL)
            {
                cur = cur -> next;
            }
            cur -> next = newNode;
        }
    }
}

void insertFirst(int val)
{
    struct Node *newNode = (struct Node*) malloc(sizeof(struct Node));
    newNode -> data = val;
    newNode -> next = NULL;
    if(head == NULL)
    {
        head = newNode;
    }
    else
    {
        newNode -> next = head;
        head = newNode;
    }
}

void insertLast(int val)
{
    struct Node *newNode = (struct Node*) malloc(sizeof(struct Node));
    newNode -> data = val;
    newNode -> next = NULL;

    if(head == NULL)
    {
        head = newNode;
    }
    else
    {
        struct Node *cur = head;
        while(cur -> next != NULL)
        {
            cur = cur -> next;
        }
        cur -> next = newNode;
    }
}

void insertAt(int pos,int val)
{
    if(pos==1)
    {
        insertFirst(val);
        return;
    }
    if(head==NULL)
    {
        printf("No linked list is being created\n");
        return;
    }
    struct Node *newNode = (struct Node*) malloc(sizeof(struct Node));
    newNode -> data = val;
    newNode -> next = NULL;

    struct Node *temp;
    temp = head;

    for(int i=2; i<pos; i++)
    {
        temp = temp -> next;
        if(temp==NULL) {
            printf("Insertion is not possible\n");
            return;
        }
    }
    newNode -> next = temp -> next;
    temp -> next = newNode;
}

void deletefirst()
{
    if(head == NULL)
    {
        printf("List is empty\n");
        return;
    }
    else
    {
        struct Node *cur;
        cur = head;
        head = head -> next;
        free(cur);
        printf("Successfully Deleted!\n\n");
    }
}

void deleteLast()
{
    if(head == NULL)
    {
        printf("List is empty\n");
        return;
    }
    else
    {
        struct Node *cur, *prev;
        cur = head;
        prev = head;
        while(cur -> next != NULL)
        {
            prev = cur;
            cur = cur -> next;
        }
        if(cur == head) head = NULL;
        else prev -> next = NULL;
        free(cur);
        printf("Successfully Deleted!\n\n");
    }
}

void deleteAt(int pos)
{
    if(head == NULL)
    {
        printf("List is empty\n");
        return;
    }
    else
    {
        struct Node *cur, *prev;
        cur = head;
        prev = head;
        for(int i=1; i<pos; i++)
        {
            if(cur == NULL)
            {
                printf("Deletion is not possible!\n");
                return;
            }
            prev = cur;
            cur = cur -> next;
        }
        if(cur == head) head = NULL;
        else
        {
            prev -> next = cur -> next;
        }
        free(cur);
        printf("Successfully Deleted!\n\n");
    }
}

void search(int val)
{
    if(head==NULL)
    {
        printf("List is empty!\n");
        return;
    }
    int index = 1;
    struct Node *cur;
    cur = head;
    while(cur != NULL)
    {
        if(cur -> data == val)
        {
            printf("%d found at position: %d\n",val,index);
            return;
        }
        cur = cur -> next;
        index++;
    }
    printf("%d is not found in the list\n",val);
}

void printNode(struct Node* cur)
{
    printf("Linked List: ");
    while(cur != NULL)
    {
        printf("%d  ",cur->data);
        cur = cur -> next;
    }
    printf("\n\n");
}

void freeTheList()
{
    struct Node *curNode = head;
    while(head != NULL)
    {
        curNode = head;
        head = head->next;
        free(curNode);
    }
}

int main()
{
    int n;
    printf("Enter the number of elements in the list: ");
    scanf("%d",&n);
    printf("Enter %d elements: ", n);
    CreatAList(n);
    printNode(head);
    printf("A linked list has been created!\n\n\n");

    while(1)
    {
        printf("1. Insert First\n");
        printf("2. Insert Last\n");
        printf("3. Insert At\n");
        printf("4. Delete First\n");
        printf("5. Delete Last\n");
        printf("6. Delete At\n");
        printf("7. Search\n");
        printf("8. Print List\n");
        printf("9. Exit\n");
        printf("Enter Choice: ");
        int choice;
        scanf("%d",&choice);
        if(choice == 1)
        {
            printf("Enter the element: ");
            int val;
            scanf("%d",&val);
            insertFirst(val);
            printf("Successfully inserted!\n\n");
        }
        else if(choice == 2)
        {
            printf("Enter the element: ");
            int val;
            scanf("%d",&val);
            insertLast(val);
            printf("Successfully inserted!\n\n");
        }
        else if(choice == 3)
        {
            printf("Enter the position (between first and last): ");
            int pos;
            scanf("%d",&pos);
            printf("Enter the element: ");
            int val;
            scanf("%d",&val);
            insertAt(pos,val);
            printf("Successfully inserted!\n\n");
        }
        else if (choice == 4) deletefirst();
        else if (choice == 5) deleteLast();
        else if (choice == 6)
        {
            printf("Enter the position: ");
            int pos;
            scanf("%d",&pos);
            deleteAt(pos);
        }
        else if(choice == 7)
        {
            printf("Enter the value: ");
            int val;
            scanf("%d",&val);
            search(val);
        }
        else if(choice == 8) printNode(head);
        else if(choice == 9) break;
        else printf("Wrong Choice Input!!\n\n");
    }
    freeTheList();
}