PHP Complete Tutorial – Learn PHP from Scratch | Esikhcha

🐘 PHP Complete Tutorial

From basic syntax to form validation — everything you need to master PHP

📖 Syntax & Variables 🔄 Loops & Functions 📦 Arrays & Superglobals 🔍 Regular Expressions 📝 Form Handling

CHAPTER 1

PHP Intro & Installation

PHP (Hypertext Preprocessor) is a widely-used, open-source server-side scripting language designed for web development. It runs on servers like Apache, Nginx, and IIS.

To run PHP, you need a local server environment like XAMPP, WAMP, MAMP or a web hosting service. PHP files have the extension .php and can contain HTML, CSS, JavaScript, and PHP code.

💡 PHP code is executed on the server, and the result is sent to the browser as plain HTML.

CHAPTER 2

PHP Syntax & Comments

PHP code is embedded in HTML using <?php ... ?> tags.

▶ Basic PHP File

<!DOCTYPE html>
<html>
<body>
<?php
// This is a single-line comment
echo "Hello, World!";  // Outputs text
# This is also a single-line comment
/*
This is a
multi-line comment
*/
?>
</body>
</html>

Output: Hello, World!

CHAPTER 3

Variables, Echo & Print

Variables in PHP start with $ followed by the variable name. They are case-sensitive and dynamically typed.

<?php $name = "John"; // string $age = 25; // integer $price = 19.99; // float $is_admin = true; // boolean // echo (no return value) echo "Hello $name"; echo "Age: " . $age; // print (returns 1, slightly slower) print "Welcome!"; // print_r (for arrays) print_r([1, 2, 3]); ?>

Hello John
Age: 25
Welcome!
Array ( [0] => 1 [1] => 2 [2] => 3 )

CHAPTER 4

Data Types & Type Casting

PHP supports: string, integer, float, boolean, array, object, NULL, resource.

<?php $x = "Hello"; // string $y = 42; // integer $z = 3.14; // float $a = true; // boolean $b = null; // NULL // Type casting $num = "123"; $int_num = (int)$num; // 123 $float_num = (float)$num; // 123.0 $str_num = (string)456; // "456" // Check type var_dump($x); // string(5) "Hello" ?>

CHAPTER 5

Strings & Numbers

<?php // String functions $text = "Hello PHP World"; echo strlen($text); // 16 echo str_word_count($text); // 3 echo strpos($text, "PHP"); // 6 echo str_replace("World", "Everyone", $text); // Number functions echo is_numeric("123"); // true echo number_format(1234.56, 2); // 1,234.56 echo rand(1, 100); // random number ?>

CHAPTER 6

Math Functions & Constants

<?php echo pi(); // 3.1415926535898 echo min(2,4,6,1); // 1 echo max(2,4,6,1); // 6 echo abs(-7); // 7 echo sqrt(64); // 8 echo round(3.6); // 4 // Define constants define("SITE_NAME", "ReadersNepal"); const VERSION = "1.0"; echo SITE_NAME; // ReadersNepal ?>

CHAPTER 7

Magic Constants

Magic constants change depending on where they are used.

<?php echo __LINE__; // Current line number echo __FILE__; // Full file path echo __DIR__; // Directory path echo __FUNCTION__; // Function name echo __CLASS__; // Class name echo __METHOD__; // Method name echo __NAMESPACE__; // Namespace name ?>

CHAPTER 8

PHP Operators

Type	Operators	Example
Arithmetic	+ – * / % **	$a + $b
Assignment	= += -= *= /=	$x += 5
Comparison	== === != !== > < >= <=	$a === $b
Logical	and or xor && \|\| !	$a && $b
String	. .=	$a . $b

<?php $a = 10; $b = 3; echo $a + $b; // 13 echo $a . $b; // "103" echo $a == "10"; // true (value) echo $a === "10"; // false (type) ?>

CHAPTER 9

If/Else, Switch, Match

<?php // If/Else $score = 85; if ($score >= 90) { echo "A"; } elseif ($score >= 80) { echo "B"; // Output: B } else { echo "C"; } // Switch $day = "Monday"; switch ($day) { case "Monday": echo "Start of week"; break; case "Friday": echo "Weekend coming"; break; default: echo "Mid week"; } // Match (PHP 8.0+) $status = match($score) { default => "Valid" }; ?>

CHAPTER 10

Loops: for, while, do-while, foreach

<?php // for loop for ($i = 1; $i <= 5; $i++) { echo $i . " "; // 1 2 3 4 5 } // while loop $j = 1; while ($j <= 3) { echo $j; $j++; } // foreach (for arrays) $colors = ["red", "green", "blue"]; foreach ($colors as $color) { echo $color; } // foreach with key $ages = ["John" => 25, "Jane" => 30]; foreach ($ages as $name => $age) { echo "$name is $age"; } ?>

CHAPTER 11

Functions

<?php // Basic function function greet($name) { return "Hello, $name!"; } echo greet("Alice"); // Default parameters function multiply($a, $b = 2) { return $a * $b; } echo multiply(5); // 10 // Variable scope $global_var = 10; function test() { global $global_var; $local_var = 5; return $global_var + $local_var; } // Anonymous function $square = function($x) { return $x * $x; }; echo $square(4); // 16 ?>

CHAPTER 12

Arrays: Indexed, Associative, Multidimensional

<?php // Indexed array $fruits = ["Apple", "Banana", "Orange"]; echo $fruits[0]; // Apple // Associative array (key/value) $person = ["name" => "John", "age" => 30, "city" => "NYC"]; echo $person["name"]; // John // Multidimensional array $matrix = [ [1, 2, 3], [4, 5, 6] ]; echo $matrix[1][2]; // 6 // Array functions echo count($fruits); // 3 array_push($fruits, "Mango"); sort($fruits); ?>

CHAPTER 13

Superglobals ($_GET, $_POST, $_SERVER, $_SESSION, $_COOKIE)

<?php // $_GET - data from URL query string // example.com/page.php?name=John $name = $_GET['name'] ?? 'Guest'; // $_POST - data from HTML forms (method="POST") $email = $_POST['email'] ?? ''; // $_SERVER - server info echo $_SERVER['REQUEST_METHOD']; // GET/POST echo $_SERVER['REMOTE_ADDR']; // Client IP // $_SESSION - persistent data across pages session_start(); $_SESSION['user_id'] = 123; // $_COOKIE - browser cookies setcookie("theme", "dark", time() + 86400); echo $_COOKIE['theme'] ?? 'light'; ?>

⚠️ Always validate and sanitize superglobal data for security!

CHAPTER 14

Regular Expressions (RegEx)

preg_match() – checks if pattern matches
preg_replace() – replaces pattern matches
preg_split() – splits string by pattern

<?php // Email validation $email = "user@example.com"; if (preg_match("/^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/", $email)) { echo "Valid email"; } // Phone number (US format) $phone = "123-456-7890"; if (preg_match("/^\d{3}-\d{3}-\d{4}$/", $phone)) { echo "Valid phone"; } // Replace digits with X $text = "My number is 12345"; $result = preg_replace("/\d/", "X", $text); echo $result; // "My number is XXXXX" // Split string $tags = "apple,banana,orange"; $arr = preg_split("/,/", $tags); // ['apple', 'banana', 'orange'] ?>

CHAPTER 15

Form Handling & Validation

Complete example with validation for required fields, email, and URL.

📝 HTML Form

<form method="POST" action="<?php echo htmlspecialchars($_SERVER['PHP_SELF']); ?>">
Name: <input type="text" name="name"><br>
Email: <input type="text" name="email"><br>
Website: <input type="text" name="website"><br>
<input type="submit" name="submit" value="Submit">
</form>

✅ PHP Validation Logic

<?php
$name = $email = $website = "";
$nameErr = $emailErr = $websiteErr = "";
if ($_SERVER["REQUEST_METHOD"] == "POST") {
// Required field validation
if (empty($_POST["name"])) {
$nameErr = "Name is required";
} else {
$name = test_input($_POST["name"]);
if (!preg_match("/^[a-zA-Z-' ]*$/", $name)) {
$nameErr = "Only letters and spaces allowed";
}
}
// Email validation
if (empty($_POST["email"])) {
$emailErr = "Email is required";
} else {
$email = test_input($_POST["email"]);
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
$emailErr = "Invalid email format";
}
}
// URL validation
if (!empty($_POST["website"])) {
$website = test_input($_POST["website"]);
if (!preg_match("/\b(?:(?:https?|ftp):\/\/|www\.)[-a-z0-9+&@#\/%?=~_|!:,.;]*[-a-z0-9+&@#\/%=~_|]/i", $website)) {
$websiteErr = "Invalid URL";
}
}
}
function test_input($data) {
$data = trim($data);
$data = stripslashes($data);
$data = htmlspecialchars($data);
return $data;
}
?>

CHAPTER 16

Complete Form with Validation

🎯 Full Registration Form Example

<?php
// Initialize variables
$name = $email = $gender = $comment = "";
$nameErr = $emailErr = $genderErr = "";
$success = false;
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$isValid = true;
// Validate Name
if (empty($_POST["name"])) {
$nameErr = "Name is required";
$isValid = false;
} else {
$name = test_input($_POST["name"]);
}
// Validate Email
if (empty($_POST["email"])) {
$emailErr = "Email is required";
$isValid = false;
} else {
$email = test_input($_POST["email"]);
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
$emailErr = "Invalid email format";
$isValid = false;
}
}
// Validate Gender
if (empty($_POST["gender"])) {
$genderErr = "Gender is required";
$isValid = false;
} else {
$gender = test_input($_POST["gender"]);
}
$comment = test_input($_POST["comment"] ?? "");
if ($isValid) {
$success = true;
}
}
function test_input($data) {
return htmlspecialchars(stripslashes(trim($data)));
}
?>
<?php if ($success): ?>
<div style="background: #dcfce7; padding: 1rem; border-radius: 8px;">
✅ Form submitted successfully!<br>
Name: <?php echo $name; ?><br>
Email: <?php echo $email; ?><br>
Gender: <?php echo $gender; ?><br>
Comment: <?php echo $comment; ?>
</div>
<?php endif; ?>
<form method="post" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>">
<label>Name: *</label>
<input type="text" name="name" value="<?php echo $name; ?>">
<span style="color:red;"><?php echo $nameErr; ?></span><br>
<label>Email: *</label>
<input type="text" name="email" value="<?php echo $email; ?>">
<span style="color:red;"><?php echo $emailErr; ?></span><br>
<label>Gender: *</label>
<input type="radio" name="gender" value="female" <?php if ($gender=="female") echo "checked"; ?>> Female
<input type="radio" name="gender" value="male" <?php if ($gender=="male") echo "checked"; ?>> Male
<span style="color:red;"><?php echo $genderErr; ?></span><br>
<label>Comment:</label>
<textarea name="comment"><?php echo $comment; ?></textarea><br>
<input type="submit" name="submit" value="Submit">
</form>

🔒 This example includes: required field validation, email format validation, XSS prevention (htmlspecialchars), and data persistence after submission.

SUMMARY

🎯 What You’ve Learned

PHP syntax, variables, data types, and operators
Conditional statements (if/else, switch, match)
Loops (for, while, foreach)
Functions (built-in and user-defined)
Arrays (indexed, associative, multidimensional)
Superglobals ($_GET, $_POST, $_SESSION, $_SERVER, $_COOKIE)
Regular expressions for pattern matching
Complete form handling with validation

💡 Next steps: Practice building real applications like contact forms, login systems, and CRUD operations with databases.