What is the single line comment in php?

Comments in PHP

A comment in PHP code is a line that is not executed as a part of the program. Its only purpose is to be read by someone who is looking at the code.

Comments can be used to:

• Let others understand your code
• Remind yourself of what you did - Most programmers have experienced coming back to their own work a year or two later and having to re-figure out what they did. Comments can remind you of what you were thinking when you wrote the code

PHP supports several ways of commenting:

Example

Syntax for single-line comments:

// This is a single-line comment

# This is also a single-line comment
?>

Try it Yourself »

Example

Syntax for multiple-line comments:

/*
This is a multiple-lines comment block
that spans over multiple
lines
*/
?>

Try it Yourself »

Example

Using comments to leave out parts of the code:

// You can also use comments to leave out parts of a code line
$x = 5 /* + 15 */ + 5;
echo $x;
?>

Try it Yourself »

Using Comments in PHP

Comments in PHP are similar to comments that are used in HTML. The PHP comment syntax always begins with a special character sequence and all text that appears between the start of the comment and the end will be ignored.

In HTML a comment's main purpose is to serve as a note to you, the web developer or to others who may view your website's source code. However, PHP's comments are different in that they will not be displayed to your visitors. The only way to view PHP comments is to open the PHP file for editing. This makes PHP comments only useful to PHP programmers.

In case you forgot what an HTML comment looked like, see our example below.

HTML Code:

PHP Comment Syntax: Single Line Comment

While there is only one type of comment in HTML, PHP has two types. The first type we will discuss is the single line comment. The single line comment tells the interpreter to ignore everything that occurs on that line to the right of the comment. To do a single line comment type "//" or "#" and all text to the right will be ignored by PHP interpreter.

PHP Code:

Psst...You can't see my PHP comments!"; // echo "nothing";
// echo "My name is Humperdinkle!";
# echo "I don't do anything either";
?>

Display:

Hello World!
Psst...You can't see my PHP comments!

Notice that a couple of our echo statements were not evaluated because we commented them out with the single line comment. This type of line commenting is often used for quick notes about complex and confusing code or to temporarily remove a line of PHP code.

PHP Comment Syntax: Multiple Line Comment

Similiar to the HTML comment, the multi-line PHP comment can be used to comment out large blocks of code or writing multiple line comments. The multiple line PHP comment begins with " /* " and ends with " */ ".

PHP Code:

Display:

Hello World!

Good Commenting Practices

One of the best commenting practices that I can recommend to new PHP programmers is....USE THEM!! So many people write complex PHP code and are either too lazy to write good comments or believe the commenting is not needed. However, do you really believe that you will remember exactly what you were thinking when looking at this code a year or more down the road?

Let the comments permeate your code and you will be a happier PHPer in the future. Use single line comments for quick notes about a tricky part in your code and use multiple line comments when you need to describe something in greater depth than a simple note.

• Go Back
• Continue

Download Tizag.com's PHP Book

If you would rather download the PDF of this tutorial, check out our PHP eBook from the Tizag.com store. Print it out, write all over it, post your favorite lessons all over your wall!

Found Something Wrong in this Lesson?

Report a Bug or Comment on This Lesson - Your input is what keeps Tizag improving with time!

What are the two ways to use single line comments in PHP?

What is multi line comment in PHP?

How do you make comments statements in PHP?

Which is the correct way to write a multiple line PHP comment?