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Tech Mahindra · PHP
Practice PHP questions specifically asked in Tech Mahindra interviews – ideal for online test preparation, technical rounds and final HR discussions.
Questions
44
Tagged for this company + subject
Company
Tech Mahindra
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Subject
PHP
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Go through each question and its explanation. Use this page for targeted revision just before your Tech Mahindra PHP round.
PHP handles exceptions using try-catch blocks. Code that might fail goes in try, and the catch block handles the thrown exception.
try { throw new Exception('Error'); } catch(Exception $e) { echo $e->getMessage(); }For complete preparation, combine this company + subject page with full company-wise practice and subject-wise practice. You can also explore other companies and topics from the links below.
The finally block always runs after try-catch, even if an exception is thrown. It's often used to close files or database connections.
try { } catch(Exception $e){ } finally { echo 'Done'; }PDO stands for PHP Data Object. It provides a database abstraction layer that works with many database systems like MySQL, SQLite, and PostgreSQL.
$pdo = new PDO('mysql:host=localhost;dbname=test','root','pass');The factorial of a number is the product of all positive integers up to that number. So 5 factorial equals 5 × 4 × 3 × 2 × 1, which is 120.
OPCache improves performance by storing precompiled PHP bytecode in memory, reducing the need for PHP to parse and compile scripts on every request.
All web routes that respond to HTTP requests in Laravel are typically defined in the routes/web.php file using simple route definitions.
Route::get('/home', [HomeController::class, 'index']);Prepared statements separate SQL logic from user input. This prevents attackers from injecting malicious SQL through form inputs or URLs.
$stmt = $pdo->prepare('SELECT * FROM users WHERE id = ?');Method overriding means redefining a parent class method inside a child class with the same name and parameters. The child version replaces the parent one when called from the child object.
class ParentClass { function greet(){ echo 'Hi'; } }
class Child extends ParentClass { function greet(){ echo 'Hello'; } }The bind_param function binds PHP variables to the SQL query placeholders before execution. It helps ensure secure and structured queries.
$stmt->bind_param('s',$name);The $_SESSION superglobal holds data for the current session, allowing values to be shared across different pages for the same user.
$_SESSION['user'] = 'John';
The $_POST superglobal is used to collect form data sent using the POST method. It is safer for confidential data.
$_REQUEST collects data from both $_GET and $_POST depending on PHP configuration. It is used for flexible form handling.
session_start() initializes session tracking in PHP. It must be called before any output is sent.
session_start(); $_SESSION['user']='John';
The count function returns the total number of elements in an array or the number of properties in an object.
count([1,2,3,4]); // 4
Access modifiers control visibility. Public means accessible everywhere. Protected means within the class and subclasses. Private means only inside the same class.
class Test { public $a; protected $b; private $c; }$this refers to the current object instance inside a class. It is used to access class properties or methods of that object.
class User { public $name; function say(){ echo $this->name; } }A for loop includes three expressions: initialization, condition, and increment or decrement.
for($i=0; $i<5; $i++){ echo $i; }Traits allow code reusability in multiple classes. They provide a way to use common methods across unrelated classes.
trait Logger { function log(){ echo 'Logging...'; } }
class App { use Logger; }The foreach loop is made for iterating arrays. It can loop through both keys and values easily.
foreach($arr as $val){ echo $val; }mysqli_fetch_assoc fetches one row from the result set and returns it as an associative array where column names are used as keys.
$row = mysqli_fetch_assoc($result);
If a function has no return statement, PHP automatically returns null. This is common for functions that only print or modify data.
function test(){} $x = test(); // nullstrlen() returns the number of characters in a string, including spaces.
strlen('Hello');array_merge() joins arrays. If keys repeat, later values overwrite earlier ones for string keys.
$result = array_merge($a,$b);
In PHP, all variables begin with a dollar sign. For example, $name equals 'John'.
$name = 'John';
PHP does not have a specific 'character' type. A single character is treated as a string of length one.
The dot operator in PHP is used for string concatenation, not addition. 10 dot 5 results in '105'.
$result = 10 . 5; // gives 105
The fgets function reads a single line from an open file until it reaches a newline or end of file.
$line = fgets($handle);
The fclose function closes an open file handle and frees the system resources associated with it.
fclose($handle);
The file_exists function checks if a given path refers to an existing file or directory and returns true or false.
if(file_exists('data.txt')) { echo 'Found'; }The session_destroy function removes all session data stored on the server. It is often used during logout to clear the user’s session.
session_destroy();
Authentication verifies the identity of a user, ensuring that the person logging in is who they claim to be before granting access to protected areas.
The json_encode function converts PHP data structures like arrays or objects into JSON strings, which can be sent over APIs or stored easily.
json_encode($data);
A 404 status code indicates that the server cannot find the requested resource. It’s one of the most common response codes on the web.
The Content-Type header tells the browser how to interpret the response data, such as text/html or application/json.
header('Content-Type: application/json');Autoloading allows PHP to automatically include the required class file when an object is created. It removes the need for manual include statements.
spl_autoload_register(function($class){ include $class.'.php'; });Output buffering temporarily holds the output before sending it to the browser. It allows manipulation of headers or compression of data before output.
ob_start(); echo 'Hello'; ob_end_flush();
Union types let you declare that a parameter or return value can accept multiple types, such as int or float. It improves type safety and flexibility.
function sum(int|float $a, int|float $b){ return $a+$b; }Named arguments allow passing arguments to functions by name instead of position, improving code readability and allowing flexible argument ordering.
displayUser(age:25, name:'John');
The mixed type allows a variable or function to accept any type, including int, float, string, array, object, or null. It’s useful for flexible APIs.
function processData(mixed $data){ return $data; }MVC stands for Model View Controller. It separates data handling (Model), presentation (View), and business logic (Controller) for better organization and maintainability.
Migrations are version control for your database. They allow you to create, modify, and share database structures across different environments easily.
php artisan make:migration create_users_table
Middleware filters HTTP requests entering your application. It’s often used for authentication, logging, and modifying requests or responses before reaching controllers.
php artisan make:middleware CheckUser
In production, sensitive error messages should not be visible to users. Instead, errors should be logged securely for developers to review later.
ini_set('display_errors',0); ini_set('log_errors',1);API keys are unique identifiers used to authenticate and track client access to an API. They help control usage and prevent unauthorized access.