Basic-Level PHP Questions

Basic-Level PHP Questions

🔹 1. What is PHP?

PHP stands for Hypertext Preprocessor. It is a server-side scripting language used to develop dynamic and interactive web pages.

🔹 2. When and why is PHP used?

PHP is used for server-side development, such as handling forms, sessions, database operations, file uploads, and more. It’s widely used because it's:

• Easy to learn

• Open-source

• Platform-independent

• Supports multiple databases

🔹 3. What are the key features of PHP?

• Open-source

• Server-side scripting

• Cross-platform (Windows, Linux, macOS)

• Embedded in HTML

• Supports many databases (MySQL, PostgreSQL, etc.)

• Large community support

• Loosely typed language

🔹 4. What is the latest version of PHP?

As of now (2025), the latest stable version is PHP 8.4. (Note: Always check php.net for the latest version.)

🔹 5. How do you write a simple PHP script?

<?php

echo "Hello, World!";

?>

🔹 6. What are variables in PHP?

Variables in PHP store data and are declared using the $ symbol:

$name = "John";

🔹 7. What are data types in PHP?

PHP supports several data types:

• Data Type	Example	Description
  String	"Hello"	Sequence of characters
  Integer	10	Whole number
  Float	10.5	Decimal number
  Boolean	true / false	Logical values
  Array	[1, 2, 3]	Collection of values
  Object	new ClassName()	Instance of a class
  NULL	NULL	No value
  Resource	mysqli_connect()	External resource (e.g., database)

🔹 8. What is the difference between echo and print in PHP?

• echo can take multiple parameters, slightly faster, no return value.

• print can only take one parameter and returns 1, so it can be used in expressions.

echo "Hello", " World";  // Valid

print "Hello";           // Valid

🔹 9. What is the difference between == and === in PHP?

• == checks for value equality (type conversion allowed).
• === checks for value and data type equality (strict comparison).

5 == "5"   // true

5 === "5"  // false

🔹 10. What is the difference between single (') and double (") quotes in PHP?

• Single quotes ' ' do not parse variables.
• Double quotes " " parse variables and escape sequences.

$name = "John";

echo 'Hello $name';  // Hello $name

echo "Hello $name";  // Hello John

🔹 11. How can you define a constant in PHP?

using define key

define("SITE_NAME", "TransSunshine");

echo SITE_NAME; //

🔹 12. What are the different types of arrays in PHP?

• Indexed arrays: Numeric keys

<?php

$fruits = ["Apple", "Banana", "Mango"];

echo $fruits[0]; // Output: Apple

?>

• Associative arrays: Named keys

<?php

$person = [

    "name" => "Lakshmi",

    "age" => 27

];

echo $person["name"]; // Output: Lakshmi

?>

• Multidimensional arrays: Arrays within arrays

<?php

$students = [

    ["Lakshmi", 27],

    ["Rahul", 25]

];

echo $students[0][0]; // Output: Lakshmi

?>

13. What is the difference between indexed and associative arrays?

• Indexed arrays use numeric indexes.
• Associative arrays use named keys.

14. How do you loop through an array in PHP?

There are many ways, but the most common and easiest is:

foreach loop

$fruits = ["Apple", "Banana", "Mango"];

foreach ($fruits as $fruit) {

    echo $fruit . "<br>";

}

 Another way: for loop (if you want to use indexes)

$fruits = ["Apple", "Banana", "Mango"];

for ($i = 0; $i < count($fruits); $i++) {

    echo $fruits[$i] . "<br>";

}

🔹 15. What are the different types of loops in PHP?

• while

• do...while

• foreach

🔹 16. How do you define a function in PHP?

function greet($name) {

    return "Hello, $name";

}

🔹 17. What are PHP superglobals? Can you name a few?

Superglobals are built-in variables accessible from anywhere:

• $_GET

• $_POST

• $_REQUEST

• $_SESSION

• $_COOKIE

• $_FILES

• $_SERVER

• $_ENV

🔹 18. What is the difference between $_GET and $_POST?

• $_GET: Data is sent via URL, visible, limited length.
• $_POST: Data is sent in the body, secure, supports large data (like file uploads).

🔹 19. How does PHP handle forms (GET vs POST)?

    PHP retrieves form input using:

$name = $_GET['name'];   // For method="GET"

$name = $_POST['name'];  // For method="POST"

🔹 20. What is the use of isset() and empty() in PHP?

• isset(): Checks if a variable is set and not NULL.
• empty(): Checks if a variable is empty (0, "", NULL, false, etc.)

isset($name);  // true if $name exists

empty($name);  // true if $name is "" or 0 or NULL

🔹 21. What is the difference between include and require in PHP?

• nclude: Gives a warning if the file is missing, and script continues.
• require: Gives a fatal error and halts(stop) execution if file is missing.

🔹 22. How do you handle errors in PHP?

•     Use try...catch with exceptions.
•     Use error reporting functions:

error_reporting(E_ALL);

ini_set("display_errors", 1);

OR

 Using try and catch (Exception Handling)

 Used for handling critical errors like database/file issues

try {

    throw new Exception("Something went wrong!");

} catch (Exception $e) {    

    echo "Error: " . $e->getMessage();

}

23. How do you start a PHP session?

session_start();

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

24. What is the difference between cookies and sessions in PHP?

• Cookies: Stored on the client-side (browser), persist across sessions.
• Sessions: Stored on the server-side, expire when the browser closes (or after timeout).