todo.c

// C program for the above approach
#include <stdio.h>
#include <stdlib.h>

// Renaming structure to avoid the
// repetitive use of struct keyword
typedef struct ToDo todo;

// Declaration of structure
struct ToDo {
	// char array as data part
	char buffer[101];

	// Pointer part to access addresses
	todo* next;

	// Count variable for counting
	// the number of nodes
	int count;
};

// Declare start pointer as null in
// the beginning
todo* start = NULL;

// Driver Code
int main()
{
	int choice;
	interface();

	while (1) {

		// Change console color and
		// text color
		system("Color 3F");

		// Clear the console
		system("cls");

		printf("1. To see your ToDo list\n");
		printf("2. To create new ToDo\n");
		printf("3. To delete your ToDo\n");
		printf("4. Exit");
		printf("\n\n\nEnter your choice\t:\t");

		// Choice from the user
		scanf("%d", &choice);

		switch (choice) {

		// Calling functions defined
		// below as per the user input
		case 1:
			seetodo();
			break;
		case 2:
			createtodo();
			break;
		case 3:
			deletetodo();
			break;
		case 4:
			exit(1);
			break;
		default:
			printf("\nInvalid Choice :-(\n");
			system("pause");
		}
	}
	return 0;
}

// Code for Splash screen
void interface()
{
	system("color 4F");
	printf("\n\n\n\n");
	printf("\t~~~~~~~~~~~~~~~~~~~~~"
		"~~~~~~~~~~~~~~~~~~~~~~~~"
		"~~~~~~~~~~~~~~~~~~~~~~~~"
		"~~~~~~~~~~~~~~~~~~~~~~~"
		"~~~~~~~~~~\n");
	printf("\t~~~~~~~~~~~~~~~~~~~~~~"
		"~~~~~~~~~~~~~~~~~~~~~~~"
		"~~~~~~~~~~~~~~~~~~~~~~~"
		"~~~~~~~~~~~~~~~~~~~~~~~~"
		"~~~~~~~~~~\n\n");
	printf("\t} : } : } : } : } : } "
		": } : } : } : "
		"WELCOME TO the TODO APP "
		"	 : { : { : { : { : { "
		": { : { : { : {\n\n");
	printf("\t~~~~~~~~~~~~~~~~~~~~~"
		"~~~~~~~~~~~~~~~~~~~~~~~~"
		"~~~~~~~~~~~~~~~~~~~~~~~~~"
		"~~~~~~~~~~~~~~~~~~~~~~"
		"~~~~~~~~~~\n");
	printf("\t~~~~~~~~~~~~~~~~~~~~~~"
		"~~~~~~~~~~~~~~~~~~~~~~~"
		"~~~~~~~~~~~~~~~~~~~~~~~"
		"~~~~~~~~~~~~~~~~~~~~~~~~"
		"~~~~~~~~~~\n");
	printf("\n\n\n\t\t\t\t\t\t\t\"
		"t\t\t\t	 "
		"@Sushant_Gaurav\n\n\n\n"
		"\n\n\n\t");

	// Pausing screen until user
	// presses any key
	system("pause");
}

// To view all the todos
void seetodo()
{
	// Clearing the console
	system("cls");

	// Pointer to the node for traversal
	todo* temp;

	// temp is made to point the
	// start of linked list
	temp = start;

	// Condition for empty linked list
	if (start == NULL)
		printf("\n\nEmpty ToDo \n\n");

	// Traverse until last node
	while (temp != NULL) {

		// Print number of the node
		printf("%d.)", temp->count);

		// Print data of the node
		puts(temp->buffer);

		// Clear output console
		fflush(stdin);

		// Going to next node
		temp = temp->next;
	}

	printf("\n\n\n");
	system("pause");
}

// Function to insert a node todo
void createtodo()
{
	// Choose choice from user
	char c;

	// Pointers to node
	todo *add, *temp;
	system("cls");

	// Infinite loop which will
	// break if "n" is pressed
	while (1) {

		printf("\nWant to add new ToDo ??"
			+ " Press 'y' for Yes and 'n' "
			+ " for No :-)\n\t\t");
		fflush(stdin);

		// Input from user
		scanf("%c", &c);

		if (c == 'n')
			break;
		else {

			// If start node is NULL
			if (start == NULL) {

				// Dynamically allocating
				// memory to the newly
				// created node
				add = (todo*)calloc(1, sizeof(todo));

				// Using add pointer to
				// create linked list
				start = add;
				printf("\nType it.....\n");

				// Input from user
				fflush(stdin);
				gets(add->buffer);

				// As first input so
				// count is 1
				add->count = 1;

				// As first node so
				// start's next is NULL
				start->next = NULL;
			}
			else {
				temp = (todo*)calloc(1, sizeof(todo));
				printf("\nType it.....\n");
				fflush(stdin);
				gets(temp->buffer);

				// Insertion is at last
				// so pointer part is NULL
				temp->next = NULL;

				// add is now pointing
				// newly created node
				add->next = temp;
				add = add->next;
			}

			// Using the concept of
			// insertion at the end,
			// adding a todo

			// Calling function to adjust
			// the count variable
			adjustcount();
		}
	}
}

// Function to delete the todo
void deletetodo()
{
	system("cls");

	// To get the numbering of the
	// todo to be deleted
	int x;

	todo *del, *temp;
	printf("\nEnter the ToDo's number"
		+ " that you want to remove.\n\t\t");

	// Checking empty condition
	if (start == NULL)
		printf("\n\nThere is no ToDo"
			+ " for today :-)\n\n\n");
	else {
		scanf("%d", &x);

		// del will point to start
		del = start;

		// temp will point to start's
		// next so that traversal and
		// deletion is achieved easily
		temp = start->next;

		// Running infinite loop so
		// that user can delete and
		// asked again for choice
		while (1) {

			// When the values matches,
			// delete the node
			if (del->count == x) {

				// When the node to be
				// deleted is first node
				start = start->next;

				// Deallocating the memory
				// of the deleted node
				free(del);

				// Adjusting the count when
				// node is deleted
				adjustcount();
				break;
			}

			if (temp->count == x) {
				del->next = temp->next;
				free(temp);
				adjustcount();
				break;
			}
			else {
				del = temp;
				temp = temp->next;
			}
		}
	}
	system("pause");
}

// Function to adjust the numbering
// of the nodes
void adjustcount()
{
	// For traversal, using
	// a node pointer
	todo* temp;
	int i = 1;
	temp = start;

	// Running loop until last node
	// and numbering it one by one
	while (temp != NULL) {
		temp->count = i;
		i++;
		temp = temp->next;
	}
}