Building a Simple Telephone Book Program in C++

When learning C++, one of the most effective ways to practice is by building simple, real-world applications. In this tutorial, we'll create a telephone book program that allows you to store and manage contacts. This project is ideal for getting familiar with structures, dynamic memory allocation, and basic I/O operations in C++.

Problem Statement

We want to create a program that:

Prompts the user for the number of contacts to be added.
Dynamically allocates memory for these contacts.
Allows the user to input names and phone numbers.
Displays all the entered contacts.
Properly deallocates the allocated memory to avoid memory leaks.

Solution: The C++ Telephone Book Program


#include <iostream>
#include <string>

using namespace std;

struct Telephone {
    string name;
    int number;
};

int main() {
    int n;
    cout << "How many contacts do you want to add? : ";
    cin >> n;

    Telephone *contacts = new Telephone[n];

    cout << "\nEnter the details for each contact: \n";
    for (int i = 0; i < n; i++) {
        cout << "\nContact " << i + 1 << ":\n";
        cout << "Name: ";
        cin >> contacts[i].name;
        cout << "Phone Number: ";
        cin >> contacts[i].number;
    }

    cout << "\n--- Phonebook Details ---\n";
    for (int i = 0; i < n; i++) {
        cout << i + 1 << ") Name: " << contacts[i].name 
             << ", Phone Number: " << contacts[i].number << "\n";
    }

    delete[] contacts;

    return 0;
}

Understanding the Code

Let's break down the code and explain the core concepts:

1. Header Files

We include two essential headers:

<iostream>: Handles input and output operations.
<string>: Provides the string class, allowing us to store and manipulate text (names in this case).

2. Dynamic Memory Allocation

Memory allocation is crucial for flexibility. Instead of declaring a static array, we use new to dynamically allocate an array based on the number of contacts specified by the user.

This ensures the program uses only as much memory as needed for the given number of contacts. Later, we deallocate this memory with delete[] to prevent memory leaks.

3. User Input and Displaying Contacts

We use a loop to gather the details for each contact:

for (int i = 0; i < n; i++) {
    cout << "Name: ";
    cin >> contacts[i].name;
    cout << "Phone Number: ";
    cin >> contacts[i].number;
}

Once the input is complete, another loop prints out the stored contact information.

4. Memory Management

After the user is done with the telephone book, we release the dynamically allocated memory:

delete[] contacts;

COFPROG

Telephone Book C++