The hello world program in PHP

1. Overview

We start learning any programming language, with the famous hello world! program. This tradition is followed religiously since the inception of software programming, and we are happy that we will support it too. We will learn the basics of PHP in this series, named “PHP – Back to basics.” Let’s start with the first article in the series.

2. What is PHP

Wikipedia defines PHP as – “Hypertext Preprocessor (or simply PHP) is a server-side scripting language designed for Web development, but also used as a general-purpose programming language.” In simple words, PHP is a general purpose programming language which powers most of the web. Notable websites like Wikipedia and Facebook are built on PHP.

3. hello world! program

3.1 Writing the program

To write the program, you can use Eclipse IDE. If you do not have eclipse already, you can follow our installation guide. Below is the hello world program written in PHP:

<?php
    echo "hello world!";
?>

3.2 Running the program

The above program is saved in a file named index.php

Assuming that we have our environment setup up and running, if not you can follow this guide to setup your environment.

We can put our index.php in the server root (root folder of the server) and open http://localhost/ in a browser.

In browser, we see following output:

hello world!

3.3 Understanding the program

PHP is an interpreted language. The PHP interpreter, an executable program reads PHP from files and runs it line by line. Our hello world program has only three lines. Let’s try to understand them:

The first line – <?php tells the PHP interpreter that it is the starting of the PHP script. Anything between <?php and ?> is treated as php program by the interpreter and is executed line by line.

The second line – echo "hello world!"; starts with a keyword echo which instructs compiler to print whatever follows to the output. Then there is a string "hello world!" , which combines up and says to compiler to print “hello world!”. In the last there is a terminator ; , which tells the interpreter that this the end of current command and you can move forward.

The third and the last line – in our program, ?> tells the interpreter that this is the end of PHP script block.

4. Conclusion

In this article, we write our first PHP program – hello world!, run it and understood it deeply. In the upcoming articles, we would explore more and will learn about variables, strings, operators and lot more things. Also, all of our code is available on GitHub.