Writing Your First PHP Script

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PHP Basic Syntax(DOCUMENTATION)

Introduction

Now that your environment is ready, it is time to write your first PHP program. This lesson covers PHP tags, the echo statement, embedding PHP in HTML, and comment styles — everything you need to start producing output.

Key Concepts

  • PHP Tags (<?php ... ?>): Delimiters that tell the server where PHP code begins and ends.
  • echo Statement: The primary way to output text and HTML from PHP.
  • Short Echo Syntax (<?= ... ?>): A shorthand for <?php echo ... ?>, commonly used inside HTML templates.
  • Case Sensitivity: PHP keywords are case-insensitive, but variable names are case-sensitive.

Real World Context

Every PHP application begins with these fundamentals. Whether you are rendering a dynamic web page, generating a JSON API response, or processing a form submission, you will use echo, PHP tags, and comments daily. Understanding how PHP mixes with HTML is essential for templating and for working with frameworks like Laravel's Blade.

Deep Dive

PHP Tags

PHP code must be enclosed in opening and closing tags:

php
<?php
// Your PHP code goes here
?>

The closing ?> tag is optional (and often omitted) in files containing only PHP code. This prevents accidental whitespace issues that can cause "headers already sent" errors.

The Echo Statement

Use echo to output text to the browser:

php
<?php
echo "Hello, World!";
?>

This sends the string "Hello, World!" as part of the HTML response.

Embedding PHP in HTML

PHP shines when mixed with HTML to create dynamic pages:

php
<!DOCTYPE html>
<html>
<head>
    <title>My First PHP Page</title>
</head>
<body>
    <h1><?php echo "Welcome to PHP!"; ?></h1>
    <p>The current year is: <?php echo date("Y"); ?></p>
</body>
</html>

The PHP interpreter processes only the code between <?php and ?> tags. Everything else is sent to the browser as plain HTML.

Short Echo Syntax

For simple output within HTML, use the shorthand <?=:

php
<p>Current time: <?= date("H:i:s") ?></p>
<!-- Equivalent to: <?php echo date("H:i:s"); ?> -->

This is cleaner and is the preferred style in modern PHP templates.

Comments in PHP

PHP supports three comment styles:

php
<?php
// Single-line comment

# Another single-line comment (shell-style)

/*
  Multi-line comment
  for longer explanations
*/

/**
 * DocBlock comment
 * Used for documentation and IDE tooling
 * @param string $name The user's name
 */

Case Sensitivity

A subtle but important rule: keywords are case-insensitive, but variable names are not.

php
<?php
ECHO "This works!";  // Keywords are case-insensitive
$name = "Alice";
// echo $Name;  // Error! Variables ARE case-sensitive

Always use consistent casing to avoid confusion.

Common Pitfalls

  1. Forgetting the semicolon — Every PHP statement must end with a semicolon (;). Missing it causes a parse error.
  2. Leaving the closing ?> tag in pure PHP files — If there is whitespace or a newline after ?>, PHP will output it. This can break headers, cookies, and JSON responses. Omit ?> in files that contain only PHP.
  3. Mixing up $name and $Name — PHP variables are case-sensitive. These are two completely different variables.

Best Practices

  1. Omit the closing ?> tag — In files that contain only PHP code, always leave off the closing tag to prevent accidental whitespace output.
  2. Use <?= ?> for output in templates — It is shorter, cleaner, and universally supported since PHP 5.4.
  3. Use DocBlock comments for functions and classes — They power IDE autocompletion and generate documentation automatically.

Summary

  • PHP code lives inside <?php ... ?> tags; the closing tag is optional in pure PHP files.
  • echo outputs text and HTML to the browser.
  • Use <?= ?> as shorthand for simple echo statements in HTML.
  • PHP keywords are case-insensitive, but variable names are case-sensitive.
  • Always end statements with a semicolon.

Code Examples

php
<?php
// hello.php - Your first PHP script
// This outputs text and the current date to the browser

echo "Hello, World!";
echo "<br>";
echo "The current date is: " . date("Y-m-d");

// The dot (.) operator concatenates strings in PHP
// date() is a built-in function that formats the current date
?>
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