C Linked List.c

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

//todo structure & pointers declaration
struct node
{
    int data;
    struct node *next;
};
struct node *head, *newnode, *temp, *backtemp;
int flagforstart = 0;
//?-------------------------------------------------------------------------
// todo function prototyping
void normalCreation();  //?---1
void insertBeginning(); //*---2
void insertEnd();       //?---3
void insertBefore();    //*---4
void insertAfter();     //?---5
void deleteStart();     //*---6
void deleteEnd();       //?---7
void deleteBefore();    //*---8
void deleteAfter();     //?---9
void deleteNode();      //*---10
void searchNode();      //?---11
void display();         //*---12
//?-------------------------------------------------------------------------
//todo function -- Normal creation 1 (done)
void normalCreation()
{
    printf("\nHow many elements You want to add initially\n");
    int n;
    scanf("%d", &n);
    for (int i = 0; i < n; i++)
    {
        if (flagforstart == 0)
        {
            head = 0;
            newnode = (struct node *)malloc(sizeof(struct node));
            printf("\nEnter The Value you want to Add : ");
            scanf("%d", &newnode->data);
            newnode->next = 0;
            head = temp = newnode;
            flagforstart++; //!indicates one linked list is added
        }
        else
        {
            newnode = (struct node *)malloc(sizeof(struct node));
            printf("\nEnter The Value you want to Add : ");
            scanf("%d", &newnode->data);
            newnode->next = 0;
            temp->next = newnode;
            temp = newnode;
            flagforstart++; //!indicates one linked list is added
        }
    }
    printf("\nThe initial Linked List is created\n");
}
//todo function -- Insert Beginning 2 (done)
void insertBeginning()
{
    if (flagforstart == 0)
    { //!if no element is present in Linked List
        newnode = (struct node *)malloc(sizeof(struct node));
        printf("\nEnter the value you want to add : ");
        scanf("%d", &newnode->data);
        newnode->next = 0; //!ab ye end hai to isko bhi zero denge neto display func me masti hoga
        head = newnode;
    }
    else
    {
        newnode = (struct node *)malloc(sizeof(struct node));
        printf("\nEnter the value you want to add : ");
        scanf("%d", &newnode->data);
        newnode->next = head;
        head = newnode;
    }
    flagforstart++;
}
//todo function -- Insert End 3 (done)
void insertEnd()
{
    if (flagforstart == 0)
    { //!if no element is present in Linked List
        newnode = (struct node *)malloc(sizeof(struct node));
        printf("\nEnter the value you want to add : ");
        scanf("%d", &newnode->data);
        newnode->next = 0; //!ab ye end hai to isko bhi zero denge neto display func me masti hoga
        head = newnode;
    }
    else
    {
        newnode = (struct node *)malloc(sizeof(struct node));
        printf("\nEnter the data you want to insert at End of Linked List: ");
        scanf("%d", &newnode->data);
        newnode->next = 0;
        temp = head; //*temporary pointer now points to head that is start of linked list
        //*now lets traverse til we get 0 in next pointer (next is the pointer which stores the value of end node )
        while (temp->next != 0)
        {
            temp = temp->next;
        }
        temp->next = newnode;
    }
    flagforstart++;
}
//todo function -- Insert Before 4 (done)
void insertBefore()
{
    if (flagforstart == 0)
    {
        printf("\nThe Linked List is Empty. Add Elements to the Linked List use this function\n");
    }
    else if (flagforstart == 1)
    {
        printf("\nEnter the Data Before which you want to add the Node : ");
        int num;
        scanf("%d", &num);
        if (head->data == num)
        {
            newnode = (struct node *)malloc(sizeof(struct node));
            printf("\nEnter the value you want to add : ");
            scanf("%d", &newnode->data);
            newnode->next = head;
            head = newnode;
            flagforstart++;
        }
        else
        {
            printf("\nNo Element As Such in The Linked List\n");
        }
    }
    else
    {
        printf("\nEnter the Data Before which you want to add the Node : ");
        int num;
        scanf("%d", &num);
        temp = head;
        while (1)
        {
            if (temp->next->data == num)
            {
                newnode = (struct node *)malloc(sizeof(struct node));
                printf("\nEnter the value you want to add : ");
                scanf("%d", &newnode->data);
                newnode->next = temp->next;
                temp->next = newnode;
                flagforstart++;
                break;
            }
            else if (temp->next->next == 0 && temp->next->data != num)
            {
                printf("\nNo Element as Such in the Linked List\n");
                break;
            }
            else
            {
                temp = temp->next;
            }
        }
    }
}
//todo function -- Insert After 5 (done)
void insertAfter()
{
    if (flagforstart == 0)
    {
        printf("\nThe Linked List is Empty. Add Elements to the Linked List use this function\n");
    }
    else
    {
        printf("\nEnter the data After which you want to add the Node : ");
        int num;
        scanf("%d", &num);
        temp = head;
        while (1)
        {
            if (temp->data == num)
            {
                newnode = (struct node *)malloc(sizeof(struct node));
                printf("\nEnter The Value you want to Add : ");
                scanf("%d", &newnode->data);
                if (temp->next == 0)
                { //*if we have last node
                    newnode->next = 0;
                    temp->next = newnode;
                }
                else
                {
                    newnode->next = temp->next;
                    temp->next = newnode;
                }
                break;
            }
            else if (temp->data != num && temp->next == 0)
            {
                printf("\nNo element as such\n");
                flagforstart--; //!no element is added here so decrement as function end pe we have ++
                break;
            }
            else
            {
                temp = temp->next;
            }
        }
        flagforstart++;
    }
}
//todo function -- Delete Start 6 (done)
void deleteStart()
{
    if (flagforstart == 0)
    {
        printf("\nThe Linked List is Empty\n");
    }
    else
    {
        printf("\nThe element you deleted is : %d\n", head->data);
        temp = head;
        head = head->next;
        free(temp);
        flagforstart--;
    }
}
//todo function -- Delete End 7 (done)
void deleteEnd()
{
    if (flagforstart == 0)
    {
        printf("\nThe Linked List is Empty\n");
    }
    else if (flagforstart == 1)
    {
        printf("\nThe element you deleted is : %d\n", head->data);
        temp = head;
        free(temp);
        flagforstart--;
    }
    else
    {
        temp = head;
        while (temp->next->next != 0)
        {
            temp = temp->next;
        }
        printf("\nThe element you deleted is : %d\n", temp->next->data);
        temp->next = 0;
        temp = temp->next;
        free(temp);
        flagforstart--;
    }
}
//todo function -- Delete Before 8 (done)
void deleteBefore()
{
    if (flagforstart == 0 && flagforstart == 1)
    {
        printf("\nTo Use This Function You must have at least 2 Elements in the Linked List\n");
    }
    else if (flagforstart == 2)
    {
        printf("\nEnter the data Before which you want to Delete the Node : ");
        int num;
        scanf("%d", &num);

        if (head->next->data == num)
        {
            temp = head;
            head = head->next;
            printf("\nElement You Deleted is : %d\n", temp->data);
            free(temp);
            flagforstart--;
        }
        else
        {
            printf("\nNo element as such :-| \n");
        }
    }
    else
    {
        printf("\nEnter the data Before which you want to Delete the Node : ");
        int num;
        scanf("%d", &num);
        temp = head;
        while (1)
        {
            if (temp->next->next->data == num)
            {
                backtemp = temp->next; //not used back temp its just wrong name
                temp->next = temp->next->next;
                printf("\nElement You Deleted is : %d\n", backtemp->data);
                free(backtemp);
                flagforstart--;
                break;
            }
            else if (temp->next->next == 0 && temp->next->data != num)
            {
                printf("\nNo element as such\n");
                break;
            }
            else
            {
                temp = temp->next;
            }
        }
    }
}
//todo function -- Delete After 9 (done)
void deleteAfter()
{
    if (flagforstart == 0 && flagforstart == 1)
    {
        printf("\nTo Use This Function You must have at least 2 Elements in the Linked List\n");
    }
    else
    {
        printf("\nEnter the data After which you want to Delete the Node : ");
        int num;
        scanf("%d", &num);
        temp = head;
        while (1)
        {
            if (temp->data == num && temp->next != 0)
            {
                if (temp->next->next == 0)
                {
                    //!when next wala is the last node
                    backtemp = temp->next;
                    temp->next = 0;
                }
                else
                { //*When next to the node we have more nodes
                    backtemp = temp->next;
                    temp->next = temp->next->next;
                }
                printf("\nElement You Deleted is : %d\n", backtemp->data);
                free(backtemp);
                flagforstart--;
                break;
            }
            else if (temp->data != num && temp->next == 0)
            {
                printf("\nNo element as such\n");
                break;
            }
            else if (temp->data == num && temp->next == 0)
            {
                printf("\nThere is no element after this node bro ..Cmon man be cool\n");
                break;
            }
            else
            {
                temp = temp->next;
            }
        }
    }
}
//todo function -- Delete Specified Node 10 (done)
void deleteNode()
{
    if (flagforstart == 0)
    {
        printf("\nThere are no Elements Present in the Linked List\n");
    }
    else if (flagforstart == 1)
    {
        printf("\nEnter the data of the node you want to delete : ");
        int num;
        scanf("%d", &num);
        if (head->data == num)
        {
            temp = head;
            printf("\nThe Element you Removed is : %d \n", temp->data);
            free(temp);
            flagforstart--;
        }
        else
        {
            printf("\nThe Data is not present :-| \n");
        }
    }
    else
    {
        printf("\nEnter the data of the node you want to delete : ");
        int num;
        scanf("%d", &num);
        temp = head;
        while (1)
        {
            if (temp->next->data == num)
            {
                backtemp = temp->next;
                temp->next = temp->next->next;
                printf("\nThe Value you Deleted is : %d\n", backtemp->data);
                free(backtemp);
                break;
            }
            else if (temp->next->next == 0)
            {
                printf("\nNo element as Such \n");
                break;
            }
            else
            {
                temp = temp->next;
            }
        }
        flagforstart--;
    }
}
//todo function -- Search Node 11 (done)
void searchNode()
{
    if (flagforstart == 0)
    {
        printf("\nThe Linked List is Empty\n");
    }
    else
    {
        printf("\nEnter the Data You want to Search : ");
        int num;
        scanf("%d", &num);
        temp = head;
        int nodeno = 1;
        while (1) //?To Start An Infinite loop
        {
            if (temp->data == num)
            {
                printf("\nThe Element is at position %d\n", nodeno);
                break;
            }
            else if (temp->next == 0)
            {
                printf("\nNo element as Such \n");
                break;
            }
            else
            {
                temp = temp->next;
                nodeno++;
            }
        }
    }
}
//todo function -- Display 12 (done)
void display()
{
    temp = head;
    if (flagforstart == 0)
    {
        printf("\nThe Linked List is Empty\n");
    }
    else
    {
        printf("\nThe Linked list is : \n");
        while (temp != 0)
        {
            if (head == 0)
            {
                printf("%d\n", head->data);
            }
            else
            {
                printf("%d\n", temp->data);
            }
            temp = temp->next;
        }
    }
}
//?-------------------------------------------------------------------------
//todo main function
int main()
{

    int option = 0;
    printf("\n***--------Main Menu--------***");
    printf("\nPress the following keys for following functions");
    printf("\n1) Initial Creation\n2) Insert Begining\n3) Insert End\n4) Insert Before\n5) Insert After\n6) Delete Start\n7) Delete End\n8) Delete Before\n9) Delete After\n10) Delete Specified Node\n11) Search Node\n12) Display\n13) Exit\n");
    do
    {
        printf("\nYou want to Perform Function No : ");
        scanf("%d", &option);
        switch (option)
        {
        case 1:
            normalCreation();
            break;
        case 2:
            insertBeginning();
            break;
        case 3:
            insertEnd();
            break;
        case 4:
            insertBefore();
            break;
        case 5:
            insertAfter();
            break;
        case 6:
            deleteStart();
            break;
        case 7:
            deleteEnd();
            break;
        case 8:
            deleteBefore();
            break;
        case 9:
            deleteAfter();
            break;
        case 10:
            deleteNode();
            break;
        case 11:
            searchNode();
            break;
        case 12:
            display();
            break;
        case 13:
            //! writing so that it does not come in default when we select option 12
            break;
        default:
            printf("\nInvalid Option key is pressed\n");
            break;
        }
    } while (option != 13);
    return 0;
}