C++ Module 00 — Namespaces, Classes, Member Functions & More

This project has been created as part of the 42 curriculum by ilnassi

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Project Structure

cpp_module_00/
├── ex00/
│   ├── Makefile
│   └── megaphone.cpp
├── ex01/
│   ├── Makefile
│   ├── main.cpp
│   ├── Contact.hpp
│   ├── Contact.cpp
│   ├── PhoneBook.hpp
│   └── PhoneBook.cpp
└── ex02/
    ├── Makefile
    ├── Account.hpp
    ├── Account.cpp
    ├── 19920104_091532.log
    └── tests.cpp

Description

This module is the entry point into object-oriented programming with C++. Coming from C, the goal is to understand the fundamental differences between the two languages and to start thinking in terms of classes, objects, and encapsulation.

The module covers three exercises of increasing complexity, each introducing new concepts that form the foundation of every C++ project that follows.

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Concepts Studied

Streams — goodbye printf

In C++ you no longer use printf or scanf. Instead:

std::cout << "Hello World" << std::endl;  // output
std::cin  >> variable;                     // input
std::getline(std::cin, line);              // read full line

Classes — the core of C++

A class is a blueprint for creating objects. It groups data and the functions that operate on that data.

class MyClass {
private:
    int _value;       // only the class can access this

public:
    MyClass(int v);   // constructor
    ~MyClass();       // destructor
    int getValue() const;  // getter
};

Private vs Public:

• private — data hidden from the outside world, accessible only through methods
• public — the interface exposed to the rest of the program

Constructors and Destructors

• Constructor — called automatically when an object is created
• Destructor — called automatically when an object is destroyed
• Initialization list — the correct C++ way to initialize attributes:

MyClass::MyClass(int v) : _value(v) {}

Static Members

Static attributes and methods belong to the class itself, not to any individual object. All instances share the same static data.

static int _nbAccounts;       // shared by ALL Account objects
static int getTotalAmount();  // callable without an instance

Formatting with <iomanip>

Used to control how output is displayed, particularly for table-like formatting:

std::cout << std::setw(10) << std::right << text << "|";  // right-aligned, 10 chars wide
std::cout << std::setfill('0') << std::setw(2) << month;  // zero-padded: "09" not " 9"

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Exercises

Exercise 00 — Megaphone

Directory: ex00/

A warm-up exercise. The program takes command-line arguments and prints them in uppercase. If no arguments are given, it prints a feedback noise message.

Concepts: argc/argv, std::toupper, std::cout

./megaphone "hello world"
# HELLO WORLD

./megaphone
# * LOUD AND UNBEARABLE FEEDBACK NOISE *

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Exercise 01 — My Awesome PhoneBook

Directory: ex01/

A command-line phonebook that supports three commands: ADD, SEARCH, and EXIT. Built using two classes — Contact and PhoneBook.

Concepts: classes, private/public, getters/setters, <iomanip>, circular buffer

Key rules:

• Maximum 8 contacts — the oldest is replaced when a 9th is added
• No dynamic memory allocation
• SEARCH displays contacts in a formatted table (10-char columns, right-aligned, truncated with . if too long)

     Index| First Name|  Last Name|   Nickname|
         0|      Mario|      Rossi|       Micio|
         1|     Luigi.|     Verdi.|    Pallina.|

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Exercise 02 — The Job Of Your Dreams

Directory: ex02/

A reverse-engineering exercise. Account.cpp was accidentally deleted. Using the provided Account.hpp, tests.cpp, and a log file, the task is to reconstruct the missing implementation so that the program's output matches the log exactly (timestamps excluded).

Concepts: static members, constructors/destructors, <ctime>, log-driven development

[timestamp] index:0;amount:42;created
[timestamp] accounts:8;total:20049;deposits:0;withdrawals:0
[timestamp] index:0;p_amount:47;withdrawal:refused
[timestamp] index:0;amount:47;closed

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How to Compile and Run

Each exercise has its own Makefile. From inside the exercise directory:

make          # compile
make clean    # remove object files
make fclean   # remove object files and executable
make re       # recompile from scratch

Compilation flags used:

-Wall -Wextra -Werror -std=c++98

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What is Forbidden

• printf, scanf, malloc, free — use C++ equivalents
• using namespace and friend keywords
• STL containers and algorithms (available only from Module 08)
• C++11 or later features — strictly C++98

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