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Putting it together

Build a working CLI app with a menu loop.

Putting it together

In the final step we combine all pieces into a complete to-do CLI. Three functions (add_task, list_tasks, complete_task) and the struct Task array work together.

In this lesson we add a third task and complete the flow. This way the add, complete, list flow works end to end.

The menu loop idea

In a real CLI app the user picks from a menu: add task, list, complete or exit. A menu loop can be built with while and switch.

while (choice != 0) {
    switch (choice) {
        case 1: count = add_task(tasks, count, title); break;
        case 2: list_tasks(tasks, count); break;
        case 3: complete_task(tasks, id); break;
    }
}

In this lesson we use a fixed flow instead of a menu: add, complete, add again, list.

Practice Add the third task and complete the flow

In the code below add the line count = add_task(tasks, count, "Reading"); after the complete_task(tasks, 1); call. This runs the full three-task flow: add, add, complete, add again, list. Output should be 1 Shopping 1, 2 Sport 0 and 3 Reading 0.

Starter code

main.c
#include <stdio.h>
#include <string.h>

struct Task {
    int id;
    char title[50];
    int done;
};

int add_task(struct Task tasks[], int count, const char *title) {
    tasks[count].id = count + 1;
    strcpy(tasks[count].title, title);
    tasks[count].done = 0;
    return count + 1;
}

void list_tasks(struct Task tasks[], int count) {
    for (int i = 0; i < count; i++) {
        printf("%d %s %d\n", tasks[i].id, tasks[i].title, tasks[i].done);
    }
}

void complete_task(struct Task tasks[], int id) {
    tasks[id - 1].done = 1;
}

int main(void) {
    struct Task tasks[10];
    int count = 0;
    count = add_task(tasks, count, "Shopping");
    count = add_task(tasks, count, "Sport");
    complete_task(tasks, 1);
    list_tasks(tasks, count);
    return 0;
}

Sample solution

main.c
#include <stdio.h>
#include <string.h>

struct Task {
    int id;
    char title[50];
    int done;
};

int add_task(struct Task tasks[], int count, const char *title) {
    tasks[count].id = count + 1;
    strcpy(tasks[count].title, title);
    tasks[count].done = 0;
    return count + 1;
}

void list_tasks(struct Task tasks[], int count) {
    for (int i = 0; i < count; i++) {
        printf("%d %s %d\n", tasks[i].id, tasks[i].title, tasks[i].done);
    }
}

void complete_task(struct Task tasks[], int id) {
    tasks[id - 1].done = 1;
}

int main(void) {
    struct Task tasks[10];
    int count = 0;
    count = add_task(tasks, count, "Shopping");
    count = add_task(tasks, count, "Sport");
    complete_task(tasks, 1);
    count = add_task(tasks, count, "Reading");
    list_tasks(tasks, count);
    return 0;
}

Expected output

1 Shopping 1
2 Sport 0
3 Reading 0

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 Add the third task

Question 
count = add_task(tasks, count, ____);  /* add third task */
Answer 
count = add_task(tasks, count, "Reading");  /* add third task */

Explanation: You added the third task with title Reading.

2 Match functions

Term Meaning
add_task adding tasks
list_tasks listing
complete_task completing
while menu loop

3 What is the best structure for a CLI menu loop?

  • A struct definition
  • Just printf
  • A single if
  • A while loop with switch Correct answer

Explanation: A while loop gives repetition, switch gives selection.

All lessons in Beginner

1 C basics

  1. What is C?
  2. Your first program
  3. Compile and run
  4. Comments
  5. printf and escapes
  6. Summary - C basics

2 Variables

  1. Declaring variables
  2. Variable assignment
  3. const
  4. Variable scope
  5. typedef
  6. Summary - Variables

3 Data types

  1. Integer types
  2. Floating-point types
  3. char
  4. sizeof
  5. Type conversion
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add and subtract
  3. Multiply and divide
  4. Menu loop
  5. Putting it together

5 Operators

  1. Arithmetic operators
  2. Assignment operators
  3. Comparison operators
  4. Logical operators
  5. Bitwise operators
  6. Summary - Operators

6 I/O

  1. printf formatting
  2. scanf
  3. Multiple inputs
  4. getchar and putchar
  5. puts and fputs
  6. Summary - I/O

7 Conditionals

  1. The if statement
  2. else and else if
  3. The switch statement
  4. The ternary operator
  5. Nested conditionals
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. The while loop
  3. The do-while loop
  4. break and continue
  5. Nested loops
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding products
  3. Calculating totals
  4. Listing the cart
  5. Putting it together

10 Arrays

  1. Declaring arrays
  2. Array access
  3. Array size
  4. Multidimensional arrays
  5. Arrays and loops
  6. Summary - Arrays

11 Strings

  1. String basics
  2. String literals
  3. strlen
  4. strcpy and strcat
  5. strcmp
  6. Summary - Strings

12 Functions

  1. Defining functions
  2. Return values
  3. Parameters
  4. Function prototypes
  5. Recursion
  6. Summary - Functions

13 Pointer basics

  1. What is a pointer?
  2. The & address operator
  3. Pointer dereference
  4. NULL
  5. Pointer arithmetic
  6. Summary - Pointer basics

14 Arrays and pointers

  1. Array name as pointer
  2. Pointer to array
  3. Passing arrays to functions
  4. Pointer loop
  5. Multidim array pointer
  6. Summary - Arrays and pointers

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 String functions

  1. strchr
  2. strstr
  3. strtok
  4. sprintf
  5. sscanf
  6. Summary - String functions

17 Structs

  1. Defining structs
  2. Using structs
  3. typedef struct
  4. Array of structs
  5. Nested structs
  6. Summary - Structs

18 Memory and stack

  1. Stack and heap
  2. Automatic storage
  3. malloc
  4. free
  5. calloc and realloc
  6. Summary - Memory and stack

19 Preprocessor

  1. #define
  2. #include
  3. Conditional compilation
  4. Macro functions
  5. Header files
  6. Summary - Preprocessor

20 Beginner final

  1. Project design
  2. Data model
  3. Functions
  4. Memory management
  5. Putting it together