Welcome to phponline.in, your trusted source for high-quality PHP tutorials. In this lesson, we’ll explore everything you need to know about comments in PHP. Comments are a crucial part of any programming language, and PHP is no exception. They help developers understand, debug, and maintain code more efficiently.
Whether you’re new to PHP or brushing up your skills, understanding how and when to use comments will dramatically improve your code readability and team collaboration.
Table of Contents:
What Are Comments in PHP?
Comments are lines of text in your PHP code that are ignored by the PHP interpreter during execution. Their main purpose is to document your code, making it easier for others (and your future self) to understand what the code does.
Comments are not displayed in the browser and do not affect the performance or output of your scripts.
Why Are Comments Important?
Using comments offers several benefits:
- Improves code readability
- Helps with debugging and maintenance
- Explains logic to other developers
- Outlines TODOs and FIXMEs
- Separates sections for better structure
Types of Comments in PHP
PHP supports three types of comments:
1. Single-line Comments
Single-line comments are used for short explanations or notes.
Syntax:
// This is a single-line comment
# This is also a single-line commentExample:
<?php
$price = 100; // Base price of the item
$tax = 0.15; # Tax rate
$total = $price + ($price * $tax); // Total price including tax
?>2. Multi-line Comments
These are ideal for longer explanations or blocking out multiple lines of code temporarily.
Syntax:
/*
This is a multi-line comment.
You can write as many lines as you want.
*/Example:
<?php
/*
This block calculates the total price
including base price and tax.
*/
$total = $price + ($price * $tax);
?>3. Documentation Comments (PHPDoc)
These are structured comments used to describe functions, variables, classes, and files. They’re often parsed by IDEs and documentation generators like phpDocumentor.
Syntax:
/**
* This function adds two numbers.
*
* @param int $a
* @param int $b
* @return int
*/
function add($a, $b) {
return $a + $b;
}Benefits of PHPDoc Comments:
- Enhances editor suggestions
- Enables automatic documentation generation
- Useful for team collaboration
Best Practices for Using Comments in PHP
- Keep comments concise and relevant
- Avoid obvious comments (e.g.,
$x = 5; // set x to 5is redundant) - Use comments to explain why, not what
- Update outdated comments to avoid confusion
- Document functions and classes with PHPDoc
- Avoid cluttering code with too many comments
When to Use Comments in PHP
Use comments when you:
- Introduce complex logic
- Work in teams
- Plan features (TODOs)
- Debug code
- Create reusable functions and classes
Example TODO and FIXME Comments:
// TODO: Add user validation
// FIXME: Resolve division by zero errorCommenting Out Code Temporarily
During development, you might want to disable parts of your code without deleting them.
Example:
<?php
/*
$price = 100;
$discount = 0.2;
$finalPrice = $price - ($price * $discount);
*/
?>This is useful for debugging or feature staging.
PHP Comment Examples in Real Scenarios
Example 1: Inline Comment
$cartTotal = $itemPrice + $shippingFee; // Adding item and shippingExample 2: Function Documentation
/**
* Calculates the area of a rectangle.
*
* @param float $length
* @param float $width
* @return float
*/
function calculateArea($length, $width) {
return $length * $width;
}Example 3: Multi-line Section Divider
/* -------------------------
User Authentication Logic
---------------------------- */Common Mistakes to Avoid
- Using outdated or incorrect comments
- Over-commenting trivial code
- Using comments as a replacement for clear code
- Ignoring documentation for public APIs
SEO Tip: Commenting Helps Content Developers Too
Although comments are ignored by PHP engines, they help SEO indirectly by improving your code structure, development process, and reducing bugs. Clean code results in better performance, which search engines value.
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Internal Links and Further Learning
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FAQs about Comments in PHP
What are the three types of comments in PHP?
Single-line, multi-line, and documentation comments.
Are PHP comments visible on the webpage?
No. Comments are ignored by the PHP interpreter and not rendered on the webpage.
Can I nest comments in PHP?
No. You cannot nest multi-line comments.
Why use PHPDoc comments?
PHPDoc enhances code understanding, IDE support, and helps generate documentation.
Do comments affect PHP performance?
No. Since comments are ignored during execution, they do not affect performance.
What’s the shortcut for commenting in PHP in IDEs?
Most IDEs use Ctrl + / for single-line commenting.