Below is a comprehensive PHP technical test revision guide with explanations and code snippets covering:

Syntax & fundamentals
Control structures (if, switch, loops)
Functions
Arrays (indexed & associative)
String manipulation
Form handling
Sessions & cookies
File handling
OOP (classes, interfaces, traits, inheritance)
Error handling
Database (PDO + prepared statements)
Security basics
Common interview logic challenges
Mini practice problems

This will simulate the kinds of tasks typically given in PHP interview technical tests.

1️⃣ PHP Fundamentals

Basic PHP Structure

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

Variables

<?php
$name = "John";
$age = 30;
$height = 5.9;
$isActive = true;

echo "Name: " . $name;
?>

Constants

<?php
define("SITE_NAME", "My Website");
echo SITE_NAME;
?>

2️⃣ Conditional Statements

If / Else

<?php
$score = 75;

if ($score >= 90) {
    echo "A Grade";
} elseif ($score >= 75) {
    echo "B Grade";
} else {
    echo "Needs Improvement";
}
?>

Ternary Operator

<?php
$age = 18;
$message = ($age >= 18) ? "Adult" : "Minor";
echo $message;
?>

Switch

<?php
$day = "Monday";

switch ($day) {
    case "Monday":
        echo "Start of week";
        break;
    case "Friday":
        echo "Almost weekend";
        break;
    default:
        echo "Midweek";
}
?>

3️⃣ Loops

For Loop

<?php
for ($i = 1; $i <= 10; $i++) {
    echo $i . "<br>";
}
?>

While Loop

<?php
$count = 1;

while ($count <= 5) {
    echo $count . "<br>";
    $count++;
}
?>

Do-While Loop

<?php
$x = 1;

do {
    echo $x . "<br>";
    $x++;
} while ($x <= 3);
?>

Foreach (Arrays)

<?php
$fruits = ["Apple", "Banana", "Orange"];

foreach ($fruits as $fruit) {
    echo $fruit . "<br>";
}
?>

Foreach with key:

<?php
$ages = [
    "John" => 25,
    "Jane" => 30
];

foreach ($ages as $name => $age) {
    echo "$name is $age years old<br>";
}
?>

4️⃣ Arrays

Indexed Array

<?php
$numbers = [10, 20, 30];
echo $numbers[0];
?>

Associative Array

<?php
$user = [
    "name" => "Alice",
    "email" => "alice@example.com"
];

echo $user["email"];
?>

Multidimensional Array

<?php
$users = [
    ["name" => "John", "age" => 25],
    ["name" => "Jane", "age" => 28]
];

echo $users[1]["name"];
?>

Common Array Functions

<?php
$numbers = [5, 2, 9, 1];

sort($numbers);
print_r($numbers);

array_push($numbers, 100);

$count = count($numbers);

$max = max($numbers);
$min = min($numbers);
?>

5️⃣ Functions

Basic Function

<?php
function greet($name) {
    return "Hello " . $name;
}

echo greet("John");
?>

Default Parameters

<?php
function multiply($a, $b = 2) {
    return $a * $b;
}

echo multiply(5); // 10
?>

Type Declarations (Modern PHP)

<?php
function add(int $a, int $b): int {
    return $a + $b;
}

echo add(3, 5);
?>

Anonymous Function

<?php
$square = function($n) {
    return $n * $n;
};

echo $square(4);
?>

6️⃣ String Manipulation

<?php
$text = " Hello World ";

echo trim($text);
echo strlen($text);
echo strtoupper($text);
echo strtolower($text);
echo str_replace("World", "PHP", $text);
?>

Explode & Implode

<?php
$csv = "apple,banana,orange";
$array = explode(",", $csv);

$newString = implode(" | ", $array);
echo $newString;
?>

7️⃣ Form Handling

HTML:

<form method="POST">
    <input type="text" name="username">
    <button type="submit">Submit</button>
</form>

PHP:

<?php
if ($_SERVER["REQUEST_METHOD"] === "POST") {
    $username = htmlspecialchars($_POST["username"]);
    echo "Hello " . $username;
}
?>

8️⃣ Sessions & Cookies

<?php
session_start();

$_SESSION["user"] = "John";

echo $_SESSION["user"];
?>

<?php
setcookie("username", "John", time() + 3600);

if (isset($_COOKIE["username"])) {
    echo $_COOKIE["username"];
}
?>

9️⃣ File Handling

Write to File

<?php
$file = fopen("test.txt", "w");
fwrite($file, "Hello File");
fclose($file);
?>

Read File

<?php
$content = file_get_contents("test.txt");
echo $content;
?>

🔟 Object-Oriented PHP

Class & Object

<?php
class Person {
    public $name;
    public $age;

    public function greet() {
        return "Hello, my name is " . $this->name;
    }
}

$person = new Person();
$person->name = "John";
echo $person->greet();
?>

Constructor

<?php
class Car {
    private $brand;

    public function __construct($brand) {
        $this->brand = $brand;
    }

    public function getBrand() {
        return $this->brand;
    }
}

$car = new Car("BMW");
echo $car->getBrand();
?>

Inheritance

<?php
class Animal {
    public function speak() {
        return "Animal sound";
    }
}

class Dog extends Animal {
    public function speak() {
        return "Bark";
    }
}

$dog = new Dog();
echo $dog->speak();
?>

Interface

<?php
interface Shape {
    public function area();
}

class Circle implements Shape {
    private $radius;

    public function __construct($radius) {
        $this->radius = $radius;
    }

    public function area() {
        return pi() * $this->radius * $this->radius;
    }
}
?>

1️⃣1️⃣ Error Handling

<?php
try {
    if (!file_exists("file.txt")) {
        throw new Exception("File not found");
    }
} catch (Exception $e) {
    echo $e->getMessage();
}
?>

1️⃣2️⃣ Database (PDO – VERY COMMON IN TESTS)

<?php
$pdo = new PDO("mysql:host=localhost;dbname=testdb", "root", "");

$stmt = $pdo->prepare("SELECT * FROM users WHERE id = :id");
$stmt->bindParam(":id", $id);
$id = 1;
$stmt->execute();

$result = $stmt->fetch(PDO::FETCH_ASSOC);
print_r($result);
?>

Insert Example

<?php
$stmt = $pdo->prepare("INSERT INTO users (name, email) VALUES (?, ?)");
$stmt->execute(["John", "john@example.com"]);
?>

1️⃣3️⃣ Common Interview Logic Questions

Reverse a String

<?php
function reverseString($str) {
    return strrev($str);
}

echo reverseString("hello");
?>

Check Palindrome

<?php
function isPalindrome($str) {
    $clean = strtolower(str_replace(" ", "", $str));
    return $clean === strrev($clean);
}
?>

Fibonacci

<?php
function fibonacci($n) {
    if ($n <= 1) return $n;
    return fibonacci($n - 1) + fibonacci($n - 2);
}
?>

Find Largest in Array

<?php
function findMax($array) {
    $max = $array[0];
    foreach ($array as $value) {
        if ($value > $max) {
            $max = $value;
        }
    }
    return $max;
}
?>

1️⃣4️⃣ Security Essentials (Often Asked)

Password Hashing

<?php
$password = "mypassword";
$hash = password_hash($password, PASSWORD_DEFAULT);

if (password_verify("mypassword", $hash)) {
    echo "Password is valid";
}
?>

Prevent SQL Injection

Use prepared statements (shown earlier).

Prevent XSS

echo htmlspecialchars($userInput);

1️⃣5️⃣ Mini Practice Technical Test

Here’s a realistic interview-style problem:

Problem:

Create a function that:

Takes an array of numbers
Removes duplicates
Sorts ascending
Returns only even numbers

<?php
function processNumbers($numbers) {
    $unique = array_unique($numbers);
    sort($unique);

    $result = [];

    foreach ($unique as $num) {
        if ($num % 2 === 0) {
            $result[] = $num;
        }
    }

    return $result;
}

print_r(processNumbers([4,2,2,7,8,4,10,3]));
?>

What They May Actually Test

Based on typical PHP technical tests, expect:

Debug broken code
Write a function from scratch
Connect to a DB
Build simple CRUD
Manipulate arrays
Validate form input
Explain OOP concepts
Secure login system

How You Should Practise (Serious Advice)

Focus on:

Writing logic cleanly
Avoiding global variables
Using functions properly
Writing secure database queries
Understanding OOP structure

PHP