Building a Console Project

Snapping functions, a class, and the STL into one real program

Big Idea: A real program is not one giant pile of code. You build it from small, well-named parts — functions, a class, and STL containers — and snap them together like LEGO bricks. In this topic we build one complete console app end to end.

By the end you will be able to:

combine a class, a std::vector, and functions into one working program,
read a complete C++ console program and predict its output,
explain how main() ties all the pieces together.

1. The plan: a tiny task manager

We will build a small program that keeps a to-do list. It stores several tasks, lets us mark one as finished, prints the list, and counts how many are done. Here is what it will print when we run it:

--- My Tasks ---
1. [x] Read a book
2. [ ] Walk the dog
3. [ ] Write C++ code
Done: 1 / 3

To get there we need three building blocks: a class for one task, an STL vector to hold many tasks, and functions to do the work. Let's build them one at a time.

2. Step 1 — a class as a blueprint

A class is a blueprint. It bundles data (what a thing knows) with behaviour (what a thing can do). Our Task knows a title and whether it is done, and it can markDone() itself.

class Task {
public:
    std::string title;        // data
    bool done;                // data

    Task(std::string t) {     // constructor: builds a Task
        title = t;
        done = false;
    }

    void markDone() {         // behaviour (a method)
        done = true;
    }

    std::string status() const {
        return done ? "[x]" : "[ ]";
    }
};

The constructor Task(std::string t) runs when a task is created and fills in the starting values.
markDone() and status() are methods — functions that belong to the class.
Don't forget the semicolon after the closing brace: };

Building a Console Project