Basic PHP syntax:

<?php //Code ?>

1	<?php //Code ?>

The default extension for file is .php
Example;

<!DOCTYPE html>
<html>
<body>
<h1>My First PHP Web Script</h1>
<?php
echo "Hello World!";
?>
</body>
</html>

<!DOCTYPE html>

<html>

<body>

<h1>My First PHP Web Script</h1>

<?php

echo "Hello World!";

</body>

</html>

Use .php extension for all php files even if it contains HTML code.

PHP Tags

Opening Tags: <?php
Closing Tag: ?> : It is essential if your code is followed by HTML but it is optional if no other code follows.

1 2	Opening Tags: <?php Closing Tag: ?> : It is essential if your code is followed by HTML but it is optional if no other code follows.

Using PHP

For your PHP script to run you need to store your files inside server root folder in many cases it is htdocs or www or public_html

Viewing PHP files locally

Make sure local web server is running and then run the file using the URL like http://localhost/config.php

Check PHP configuration

Before starting you must check your PHP server is up and running and check how PHP is configured.

Create a blank file config.php

<?php phpinfo();?>

1	<?php phpinfo();?>

Load the file in the browser

If you have saved the file in www directory you can load the file with localhost/config.php

Before going further make sure you have your PHP file running to make sure everything is working correctly. Please make a note of main configuration file that is php.ini you may need to edit this file.

Comments and Whitespace

Comments in PHP are the lines of that are not read/executed. Comments make the code easier to read. Another reason to use comments is to disable part of code temporarily.

<?php
// This is single line comment

#This is also single line comment

/* This is a multi-line comment 
You can go in next line
If a comment is long */
?>

<?php

// This is single line comment

#This is also single line comment

/* This is a multi-line comment

You can go in next line

If a comment is long */

Difference Between single and double Quotes

$title = 'The Nomimi\’s guide to escape';
echo $title;

1 2	$title = 'The Nomimi\’s guide to escape'; echo $title;

In PHP we use single or double quotes for a string. You can use any of these, but there is an important difference in how they work.

Example:

$title = 'The Kritika’s guide to learn';

1	$title = 'The Kritika’s guide to learn';

If you run these code you will get an error. The problem here is that quotes must be in matching pairs.

How we can remove the error?

Inserting a black slash in front of the apostrophe.

$title = 'The Kritika\’s guide to learn';
echo $title;

1 2	$title = 'The Kritika\’s guide to learn'; echo $title;

The syntax error has been corrected. This is known as an escape sequence.

Problem: The main problem with escape string is that it looks ugly when there are lots of single codes inside a string.

2) Using double quotes:
Example 1:

$title = "The Kritika's guide to learn";
echo $title;

1 2	$title = "The Kritika's guide to learn"; echo $title;

Another difference between single and double quotes:

Example 1: When using single quotes to echo something

$title = "The Kritika's guide to learn";
echo 'this is $title';

1 2	$title = "The Kritika's guide to learn"; echo 'this is $title';

An output of this: This is

this is $title

1	this is $title

Example 1: When using double quotes to echo something

$title = "The Kritika's guide to learn";
echo "this is $title";

1 2	$title = "The Kritika's guide to learn"; echo "this is $title";

An output of this:

This is The Kritika's guide to learn

1	This is The Kritika's guide to learn