PHP fresher interview question and answer

Umar Farooque Khan
6 min readNov 18, 2023

Question 1:

Explain the difference between GET and POST methods in PHP.

Answer:

The GET method is used to send data to the server as part of the URL, while the POST method sends data in the body of the HTTP request. GET is suitable for less sensitive data, like search queries, while POST is used for more confidential information, like login credentials.

Question 2:

What is the purpose of the echo statement in PHP?

Answer:

the echo statement is used to output one or more strings. It is often used to display content, such as HTML or plain text, on a web page. The echo statement can output multiple parameters, separated by commas, and it does not require parentheses.

In this example, the echo statement is used to output the string stored in the variable $message.

You can also use echo with multiple parameters:

In this example, the echo statement outputs two strings and a line break.

It’s important to note that echo is not a function but a language construct, so it doesn't require parentheses if you're only passing one parameter. However, if you are using parentheses, they are still allowed

Question 3:

Explain the use of the include and require statements in PHP.

Answer:

Both include and require are used to include the content of a file in another PHP file. The key difference is that if require fails to include the file, it produces a fatal error and halts the script, whereas include only produces a warning.

<?php
// Using include
include 'header.php';

// Using require
require 'footer.php';
?>

Question 4:

What is the purpose of the isset function in PHP?

Answer:

The isset function is used to determine if a variable is set and is not NULL. It returns true if the variable exists and has a value other than null, and false otherwise.

<?php
$name = "John";

if (isset($name)) {
echo "The variable is set.";
} else {
echo "The variable is not set.";
}
?>

Question 5:

Explain the use of sessions in PHP.

Answer:

Sessions in PHP are used to store user-specific information across multiple pages. The session_start() function initializes a session, and $_SESSION is used to store and retrieve session variables.

<?php
session_start();
$_SESSION['username'] = 'john_doe';
echo "Session variable set.";
?>

Question 6:

What is the purpose of the header function in PHP?

Answer:

The header function is used to send raw HTTP headers. It is often used for redirection and setting content types.

<?php
header("Location: https://www.example.com");
exit();
?>

Question 7:

Explain the difference between == and === in PHP.

Answer:

== is a loose comparison that only checks if the values are equal, while === is a strict comparison that checks if the values and types are equal.

<?php
$num1 = 5;
$num2 = "5";

// Loose comparison
if ($num1 == $num2) {
echo "Equal";
} else {
echo "Not equal";
}

// Strict comparison
if ($num1 === $num2) {
echo "Equal";
} else {
echo "Not equal";
}
?>

Question 8:

What is the purpose of the foreach loop in PHP?

Answer:

The foreach loop is used to iterate over arrays or other iterable objects. It simplifies the process of iterating through each element without the need for manual indexing.

<?php
$colors = array("red", "green", "blue");

foreach ($colors as $color) {
echo $color . "<br>";
}
?>

Question 9:

Explain the concept of function overloading in PHP.

Answer:

PHP does not support function overloading in the traditional sense, where multiple functions have the same name with different parameter lists. However, you can use default parameter values or variable-length argument lists to achieve similar functionality.

<?php
function greet($name, $greeting = "Hello") {
echo $greeting . ", " . $name . "!";
}

greet("John"); // Outputs: Hello, John!
greet("Jane", "Good morning"); // Outputs: Good morning, Jane!
?>

Question 10:

What is the purpose of the mysqli extension in PHP?

Answer:

The mysqli extension is used for interacting with MySQL databases in PHP. It provides an object-oriented interface and supports prepared statements, transactions, and other advanced features.

<?php
$conn = new mysqli("localhost", "username", "password", "database");

if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}

echo "Connected successfully";
$conn->close();
?>

Question 11:

Explain the concept of a trait in PHP.

Answer:

A trait in PHP is a mechanism for code reuse in single inheritance languages. It allows developers to reuse methods in multiple classes. Traits are similar to classes, but they are intended to group functionality in a fine-grained and consistent way.

<?php
trait Logger {
public function log($message) {
echo "Logging: " . $message;
}
}

class User {
use Logger;
}

$user = new User();
$user->log("User created");
?>

Question 12:

What is the purpose of the array_merge function in PHP?

Answer:

The array_merge function is used to merge two or more arrays into a single array. It takes multiple arrays as arguments and returns a new array with elements from all the input arrays.

<?php
$array1 = array("a", "b");
$array2 = array("c", "d");

$mergedArray = array_merge($array1, $array2);
print_r($mergedArray);
// Outputs: Array ( [0] => a [1] => b [2] => c [3] => d )
?>

Question 13:

Explain the purpose of the filter_var function in PHP.

Answer:

The filter_var function is used for filtering variables with the specified filter. It is commonly used for validating and sanitizing user input, such as filtering input as an email or removing unwanted characters.

<?php
$email = "john.doe@example.com";

if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
echo "Valid email address";
} else {
echo "Invalid email address";
}
?>

Question 14:

What is the purpose of the PDO extension in PHP?

Answer:

The PDO (PHP Data Objects) extension is a database access layer providing a uniform method of access to multiple databases. It supports various database management systems and provides a consistent interface for database interactions.

<?php
try {
$pdo = new PDO("mysql:host=localhost;dbname=testdb", "username", "password");
echo "Connected successfully";
} catch (PDOException $e) {
echo "Connection failed: " . $e->getMessage();
}
?>

Question 15:

Explain the use of the ternary operator (? :) in PHP.

Answer:

The ternary operator is a shorthand way of writing an if-else statement. It has the form condition ? expr1 : expr2, where if the condition is true, it returns expr1; otherwise, it returns expr2.

<?php
$age = 20;

$message = ($age >= 18) ? "You are an adult" : "You are a minor";
echo $message;
// Outputs: You are an adult
?>

Question 16:

What is the purpose of the array_push function in PHP?

Answer:

The array_push function is used to add one or more elements to the end of an array. It modifies the array and returns the new number of elements in the array.

<?php
$fruits = array("apple", "banana");

array_push($fruits, "orange", "grape");
print_r($fruits);
// Outputs: Array ( [0] => apple [1] => banana [2] => orange [3] => grape )
?>

Question 17:

Explain the purpose of the unlink function in PHP.

Answer:

The unlink function is used to delete a file in PHP. It requires the filename as an argument and returns true on success or false on failure.

<?php
$filename = "example.txt";

if (unlink($filename)) {
echo "File deleted successfully";
} else {
echo "Unable to delete the file";
}
?>

Question 18:

What is the purpose of the array_key_exists function in PHP?

Answer:

The array_key_exists function is used to check if a specific key exists in an array. It returns true if the key exists and false otherwise.

<?php
$person = array("name" => "John", "age" => 25);

if (array_key_exists("name", $person)) {
echo "Key 'name' exists in the array.";
} else {
echo "Key 'name' does not exist in the array.";
}
?>

Question 19:

Explain the purpose of the strlen function in PHP.

Answer:

The strlen function is used to find the length (number of characters) of a string. It returns an integer representing the length of the string.

<?php
$str = "Hello, World!";
$length = strlen($str);
echo "Length of the string: " . $length;
// Outputs: Length of the string: 13
?>

Conclusion :

These questions cover various aspects of PHP and are designed to assess a freshers knowledge and understanding of the language. Understanding these fundamentals is crucial for building a strong foundation in PHP development.

  1. PHP Tricky Interview Question and answer
  2. Setup Multiple PHP Version On Mac
  3. Laravel Interview Question and answer
  4. JavaScript Tricky Question
  5. JavaScript Array Interview Questions

--

--

Umar Farooque Khan

Experienced software developer with a passion for clean code and problem-solving. Full-stack expertise in web development. Lifelong learner and team player.