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cpp-primer-programa

Our First Program in C++

  • 4 min
  • Beginner

Now that we have our working environment set up, whether it’s Visual Studio, Visual Studio Code and GCC (or another you have chosen), it’s time to see our first program.

This first program will be a console application that simply displays “Hello World” on the screen. It’s simple, but it serves to check that everything is correct and as a starting point.

The “Hello, World!” program is a programming classic, used in many languages as a first application.

So, assuming you already have your favorite IDE installed and configured correctly, let’s see our first code 👇.

Creating a New C++ Project

We start by creating a new folder for our project, for example HelloWorld, and inside it a text file called main.cpp.

You could choose any other name

Write the following code in the main.cpp file:

// Include the standard library for input and output
#include <iostream>

// Main function where the execution of the program begins
int main() { 
	// Print the message to the console
    std::cout << "Hello World from LuisLlamas.es!" << std::endl;

	 // Indicate that the program finished correctly
    return 0;
}
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Now, run this code by pressing F5 (it’s the same key in both Visual Studio and Visual Studio Code) and we’ll see what appears on the screen.

Hello World from LuisLlamas.es!
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What’s happening here? When you run this program, the compiler translates the source code you wrote into a language the computer can understand.

  1. The execution flow begins in the main() function
  2. When it reaches the line containing std::cout, the program displays the message “¡Hola, Mundo!” to the console.
  3. Execution ends with return 0;, indicating everything went well.

Let’s look at it in depth

Code Explanation

Let’s look at each part in depth

int main()

In C++, every program must have a main() function, which is the entry point where execution begins.

  • int before main indicates that the function returns an integer value (see return 0 below).

#include <iostream>

The #include keyword tells the compiler to include the contents of the iostream library before compiling the code.

This library contains functions for performing input and output tasks, such as displaying information on the console (for example std::cout and std::endl, which we see below)

std::cout << "Hello, World!" << std::endl;

This line is what makes the program print the message to the console (using the functions from iostream)

  • std::cout is used to print information to the console.
  • The << operator is the insertion operator that “sends” the text "Hello, World!" to the output stream.
  • std::endl is used to insert a line break after the output (so the message doesn’t stay on the same line as the console cursor).

return 0;

This line indicates that the main() function ends correctly and returns the value 0 to the operating system. This indicates there were no errors during execution, and it’s considered good practice to indicate the program has ended successfully.

Expanding the Program

The program we made is very simple. Let’s see some modifications you can make to practice.

Modify the Message

You can change the message printed to the console. Simply modify the text between the quotes.

std::cout << "Welcome to programming in C++" << std::endl;
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More Output Lines

You can add more output lines with multiple std::cout statements.

std::cout << "Hello, World!" << std::endl;
std::cout << "This is my first program in C++." << std::endl;
std::cout << "I'm learning to program!" << std::endl;
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Use Variables

As you progress, you’ll learn to use variables in C++. Here’s a simple example with a string variable.

#include <iostream>
#include <string>

int main() {
    std::string greeting = "Hello, World!";
    std::cout << greeting << std::endl;
    return 0;
}
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In this case, we’ve introduced a variable called greeting that contains the message, and then we print it to the console.

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