PHP Comments

In PHP, comments are used to annotate the code and make it easier to understand. They are ignored by the PHP interpreter and do not affect the execution of the script. PHP supports several types of comments:

Single-Line Comments

Single-line comments are used for short explanations or notes. There are two ways to write single-line comments in PHP:

Double Slash (//):

php
<?php
        // This is a single-line comment
        echo "Hello, World!";
    ?>

Hash (#):

php
<?php
        # This is also a single-line comment
        echo "Hello, World!";
    ?>

Multi-Line Comments

Multi-line comments are useful for longer explanations or disabling multiple lines of code. They start with /* and end with */.

php
<?php
        /*
        This is a multi-line comment.
        It can span multiple lines.
        */
        echo "Hello, World!";
    ?>

Examples of Using Comments

Explaining Code

Use comments to explain what the code does, which is helpful for others reading your code or for your future self.

php
<?php
        // Define a variable with a greeting message
        $greeting = "Hello, World!";
    
        // Output the greeting message to the browser
        echo $greeting;
    ?>

Temporarily Disabling Code

Comments can be used to disable code temporarily for debugging purposes.

php
<?php
        $x = 10;
        $y = 20;
    
        // Comment out the next line to disable addition
        // $result = $x + $y;
    
        // Use multiplication instead
        $result = $x * $y;
    
        echo $result; // Outputs 200
    ?>

Documentation Blocks

For more detailed documentation, especially for functions and classes, use PHPDoc comments. PHPDoc comments start with /** and end with */. They can include annotations to describe the function, its parameters, and return values.

php
<?php
        /**
         * Adds two numbers together.
         *
         * @param int $a The first number.
         * @param int $b The second number.
         * @return int The sum of the two numbers.
         */
        function add($a, $b) {
            return $a + $b;
        }
    
        echo add(5, 3); // Outputs 8
    ?>

Summary

Single-line comments: Use // or #.
Multi-line comments: Use /* ... */.
PHPDoc comments: Use /** ... */ for detailed documentation, especially for functions and classes.

Using comments effectively can greatly improve the readability and maintainability of your code.

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