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Entry PHP Interview Questions

Curated Entry-level PHP interview questions for developers targeting entry positions. 15 questions available.

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PHP Interview Questions & Answers

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Welcome to our comprehensive collection of PHP interview questions and answers. This page contains expertly curated interview questions covering all aspects of PHP, from fundamental concepts to advanced topics. Whether you're preparing for an entry-level position or a senior role, you'll find questions tailored to your experience level.

Our PHP interview questions are designed to help you:

  • Understand core concepts and best practices in PHP
  • Prepare for technical interviews at all experience levels
  • Master both theoretical knowledge and practical application
  • Build confidence for your next PHP interview

Each question includes detailed answers and explanations to help you understand not just what the answer is, but why it's correct. We cover topics ranging from basic PHP concepts to advanced scenarios that you might encounter in senior-level interviews.

Use the filters below to find questions by difficulty level (Entry, Junior, Mid, Senior, Expert) or focus specifically on code challenges. Each question is carefully crafted to reflect real-world interview scenarios you'll encounter at top tech companies, startups, and MNCs.

Questions

15 questions
Q1:

What is PHP and where is it commonly used?

Entry

Answer

PHP is a server-side scripting language used to build dynamic websites. It runs on the server, generates HTML, and integrates well with databases like MySQL.
Quick Summary: PHP (Hypertext Preprocessor) is a server-side scripting language designed for web development. Runs on the server and generates HTML sent to the browser. Powers 77% of websites including WordPress, Facebook (historically). Easy to embed in HTML files. Runs on Linux/Windows/Mac via Apache or Nginx with PHP-FPM. Modern PHP (8+) is fast, type-safe, and supports OOP fully.
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Q2:

What does server-side scripting mean in PHP?

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Answer

Server-side scripting means PHP code executes on the server and outputs HTML to the client. The browser never sees the PHP code.
Quick Summary: Server-side scripting means the code runs on the web server, not in the browser. PHP processes the request, executes logic (DB queries, business rules), and generates the output (HTML or JSON) that is sent to the client. The client never sees PHP code - only the output. Contrast with client-side scripting (JavaScript) which runs in the browser.
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Q3:

What is the difference between echo and print?

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Answer

echo outputs text faster and accepts multiple parameters. print returns 1 and can be used in expressions.
Quick Summary: echo: outputs one or more strings, slightly faster, no return value, can use without parentheses. print: outputs one string and returns 1, can be used in expressions. In practice they're interchangeable for simple output. echo is more commonly used. Neither is a function - both are language constructs. echo "Hello"; is the standard way to output text in PHP.
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Q4:

What are PHP variables and how are they declared?

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Answer

PHP variables start with $ and are dynamically typed, meaning type is assigned at runtime.
Quick Summary: PHP variables start with $ sign followed by a letter or underscore. Dynamically typed - no type declaration needed (though type hints are supported in PHP 7+). $name = "Alice"; $age = 25; $price = 9.99; $active = true. Variable names are case-sensitive. PHP 8 added typed properties and union types. Variables don't need to be declared before use.
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Q5:

What are PHP data types?

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Answer

PHP supports scalars (string, int, float, bool), compound types (array, object), and special types (null, resource).
Quick Summary: PHP data types: Scalar (int, float, string, bool), Compound (array, object), Special (null, resource). PHP is dynamically typed - a variable can change type. PHP 8 added union types (int|string), nullable types (?string), enums, and fibers. Use gettype() to check runtime type. Strong type declaration per file with declare(strict_types=1).
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Q6:

What is an associative array in PHP?

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Answer

An associative array uses named keys instead of numeric indexes. Useful for key-value mappings.
Quick Summary: Associative array uses string keys instead of numeric indexes. $user = ["name" => "Alice", "age" => 25]. Access: $user["name"]. Add: $user["email"] = "alice@example.com". Remove: unset($user["age"]). Check key exists: array_key_exists("name", $user) or isset($user["name"]). Iterate: foreach($user as $key => $value). Like a dictionary/hash map in other languages.
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Q7:

What is the difference between == and === in PHP?

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Answer

== compares values with type juggling. === compares both value and type.
Quick Summary: == (loose comparison): compares values with type coercion - "1" == 1 is true, "" == false is true, "0" == false is true. === (strict comparison): compares both value and type - "1" === 1 is false. Always use === in PHP to avoid unexpected type juggling behavior. The loose comparison table in PHP has many non-obvious results that cause bugs.
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Q8:

What are PHP superglobal variables?

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Answer

Superglobals ($_GET, $_POST, $_SESSION, $_COOKIE, $_SERVER) are built-in arrays available globally.
Quick Summary: Superglobals are built-in global arrays accessible from any scope. $_GET (URL query params), $_POST (form data), $_REQUEST (GET+POST+COOKIE), $_SESSION (session data), $_COOKIE (cookie values), $_SERVER (server/request info), $_FILES (file upload data), $_ENV (environment variables), $GLOBALS (all global variables). Always validate and sanitize superglobal data before use.
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Q9:

What is the role of $_GET and $_POST?

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Answer

$_GET gets URL parameters. $_POST retrieves data sent through the request body, often for forms.
Quick Summary: $_GET: data from URL query string (?name=Alice&age=25). Visible in URL, bookmarkable, cached. Use for read operations (search, filtering). $_POST: data from form body (not in URL). More secure for sensitive data, not cached. Use for write operations (login, form submission). GET has length limits; POST supports large data and file uploads. Validate both before use.
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Q10:

What is a session in PHP?

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Answer

Sessions store user-specific data on the server and persist across requests.
Quick Summary: Session stores data on the server between requests. session_start() initializes it. Data stored in $_SESSION["key"] = value. Session ID sent to client via cookie (PHPSESSID). On next request, client sends the ID and PHP loads the session data. Sessions expire on browser close (or timeout). More secure than cookies (data on server). Store user ID in session, not sensitive data like passwords.
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Q11:

What is a cookie in PHP?

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Answer

A cookie stores small data in the user’s browser for preferences or authentication.
Quick Summary: Cookies store small data in the browser sent with every request to the domain. setcookie("name", "value", expiry, path, domain, secure, httponly). Accessible via $_COOKIE["name"]. Persist across browser sessions (based on expiry). Less secure than sessions (data on client). Use for: remember me functionality, user preferences, tracking. Set HttpOnly=true (prevents JS access) and Secure=true (HTTPS only).
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Q12:

What is the include statement used for?

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Answer

include loads and executes a file at runtime to reuse common code.
Quick Summary: include() inserts the content of one PHP file into another at runtime. If the file is not found, it shows a warning but script continues. Use for optional file inclusions (template partials, optional config). include_once ensures the file is included only once even if include is called multiple times - prevents function redeclaration errors.
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Q13:

What is the difference between include and require?

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Answer

include gives a warning on failure; require stops execution with a fatal error.
Quick Summary: include: shows warning if file not found, script continues. require: shows fatal error if file not found, script stops. Use require for files that are essential (DB config, core functions) - the app can't run without them. Use include for optional files. Both have _once variants that prevent re-including the same file: require_once and include_once.
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Q14:

What is form handling in PHP?

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Answer

Form handling retrieves data using $_GET or $_POST and includes validation and sanitization steps.
Quick Summary: PHP form handling: HTML form POSTs to PHP script. PHP reads $_POST["fieldname"] for each field. Validate: check required fields are set and not empty, validate format (email, numbers). Sanitize: strip or escape dangerous characters (htmlspecialchars for output, parameterized queries for DB). Respond: process data, redirect with header() to prevent double-submit, or show errors.
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Q15:

What is the purpose of htmlspecialchars()?

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Answer

htmlspecialchars() converts < > & characters into HTML entities to prevent XSS attacks.
Quick Summary: htmlspecialchars() converts special HTML characters to their entities: & to &, < to <, > to >, " to ". Use before outputting user-supplied data in HTML to prevent XSS (Cross-Site Scripting) attacks. Always use: echo htmlspecialchars($userInput, ENT_QUOTES, "UTF-8"). htmlentities() converts more characters but htmlspecialchars() is usually sufficient.
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Curated Sets for PHP

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People Also Ask - Related PHP Questions

What is PHP and where is it commonly used?
What does server-side scripting mean in PHP?
What is the difference between echo and print?
What are PHP variables and how are they declared?
What are PHP data types?
What is an associative array in PHP?
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