MODULE 2: PHP Syntax and Basic Concepts

Notice: Function _load_textdomain_just_in_time was called incorrectly. Translation loading for the health-check domain was triggered too early. This is usually an indicator for some code in the plugin or theme running too early. Translations should be loaded at the init action or later. Please see Debugging in WordPress for more information. (This message was added in version 6.7.0.) in /home/yogisv5/sitesbyyogi.com/wp-includes/functions.php on line 6260
MODULE 2: PHP Syntax and Basic Concepts - SitesByYogi

StreetGeek Academy · PHP Foundations

🧩 Module 2: PHP Syntax and Basic Concepts

Objective: Learn the foundational syntax and data handling structures of PHP — including variables,
data types, constants, and debugging functions.

🔹 1. PHP Tags and Comments

Every PHP file starts and ends with PHP tags:

<?php
    // Your code goes here
?>

These tags tell the server where PHP code begins and ends. Anything outside them is treated as plain HTML.

💬 Comments

Comments let you explain your code and are ignored by PHP when running.

<?php
// Single-line comment
# Also a single-line comment
/*
   Multi-line
   comment
*/
?>

🧠 Best practice: Use comments to describe what your code does — especially when defining functions or logic.

🔹 2. Variables

Variables in PHP store data. They always start with a $ sign and are case-sensitive.

<?php
$name = "Yogi";
$age = 30;
echo $name; // Outputs: Yogi
?>

🧩 Naming Rules:

Must start with $
Must begin with a letter or underscore
Cannot contain spaces or start with a number
Are case-sensitive ($name ≠ $Name)

🔹 3. Data Types

PHP automatically determines a variable’s type based on its value. The main data types are:

Type	Example	Description
String	`"Hello, StreetGeek"`	Text data
Integer	`25`	Whole number
Float / Double	`3.14`	Decimal number
Boolean	`true` or `false`	Logical value
Array	`[1, 2, 3]` or `array("red", "blue")`	Multiple values
NULL	`NULL`	Empty or undefined variable
Object	`new ClassName()`	Instance of a class

🔹 4. Constants

Constants are like variables — but their values cannot change once defined.

<?php
define("SITE_NAME", "StreetGeek Academy");
echo SITE_NAME;
?>

You can also use:

const VERSION = "1.0";

🔹 5. String Concatenation & Interpolation

🧩 Concatenation

Join strings using a dot (.):

$name = "Yogi";
echo "Hello " . $name . "!";

🧩 Interpolation

If you use double quotes, variables are automatically inserted into strings:

$name = "Yogi";
echo "Hello $name!";

Single quotes (' ') do not parse variables:

echo 'Hello $name!'; // Outputs literally: Hello $name!

🔹 6. Debugging with `var_dump()`

Debugging means understanding what data your variables actually hold.

$city = "Richmond";
var_dump($city);

Output example:

string(8) "Richmond"

You can also inspect multiple values:

$name = "Yogi";
$age = 30;
$is_student = true;

var_dump($name, $age, $is_student);

🧩 Hands-On Practice

Exercise 1: Variables and Strings

Create a new file named variables.php in your php-basics folder and add:

<?php
$name = "Yogi";
$language = "PHP";
echo "Hello $name, welcome to $language programming!";
?>

✅ Output should be:

Hello Yogi, welcome to PHP programming!

Exercise 2: Data Type Practice

Add this code below your first example:

<?php
$name = "StreetGeek Academy";
$students = 100;
$rating = 4.9;
$is_open = true;
$launch_year = NULL;

var_dump($name, $students, $rating, $is_open, $launch_year);
?>

✅ Check the output — PHP tells you the data type and value of each variable.

Exercise 3: Constants and Concatenation

Create a file named constants.php:

<?php
define("ACADEMY", "StreetGeek Academy");
const FOUNDED = 2025;

echo "Welcome to " . ACADEMY . "!";
echo "<br>";
echo "Established in " . FOUNDED . ".";
?>

✅ Output:

Welcome to StreetGeek Academy!
Established in 2025.

Exercise 4: Debug Challenge

Create a script debug.php with these lines:

<?php
$students = "50";
$enrolled = 50;
if ($students === $enrolled) {
    echo "They are equal.";
} else {
    echo "They are not equal.";
}
?>

✅ What happens?
=== checks for both value and type, so "50" (string) ≠ 50 (integer).
🧠 Takeaway: Always be aware of your variable types!

📝 Module 2 Quiz

#	Question	Options	Correct
1	What symbol must all variables begin with?	a) # · b) $ · c) %	b
2	Which function displays data type and value?	a) print() · b) var_dump() · c) inspect()	b
3	How do you define a constant?	a) set(“PI”, 3.14) · b) const PI = 3.14 · c) define(“PI”, 3.14)	c
4	What is the result of `'Hello $name'` if `$name = "Yogi"`?	a) Hello Yogi · b) Hello $name · c) Error	b
5	What is the difference between `==` and `===`?	a) None · b) == compares values, === compares values and types	b

💪 Challenge Task – Personal Bio Page

Objective: Create a PHP page that introduces yourself using variables, constants, and HTML.

Create a new file bio.php inside your php-basics folder.
Add variables for your:
- Name
- Age
- Favorite language
- Hobby
Create a constant called ACADEMY = "StreetGeek Academy".
Output a small HTML profile page like this:

<!DOCTYPE html>
<html>
<head><title>About Me</title></head>
<body>
<h1>Welcome to <?php echo ACADEMY; ?></h1>
<p>My name is <?php echo $name; ?>.</p>
<p>I’m <?php echo $age; ?> years old and I love coding in <?php echo $language; ?>.</p>
<p>My favorite hobby is <?php echo $hobby; ?>.</p>
</body>
</html>

✅ Bonus: Use var_dump() to check the data types of your variables at the end of the page.

🧾 Submission Checklist

✅ variables.php → shows personalized message
✅ constants.php → uses both define() and const
✅ debug.php → demonstrates strict comparison
✅ bio.php → personal info using variables + constants
✅ Quiz completed

🏁 Next Step: In Module 3, you’ll use what you’ve learned here to perform calculations and logic with PHP —
mastering operators and expressions to build functional scripts like a discount calculator.