Why variables do not persist between requests in PHP - Quick Recap

Recall & Review

beginner

Why do variables in PHP not keep their values between different web requests?

Because each web request starts a new PHP process, variables are created fresh and lost when the script ends. PHP does not remember variable values automatically between requests.

beginner

What happens to PHP variables after a web page finishes loading?

All PHP variables are destroyed when the script finishes running. The server forgets their values because PHP runs scripts from scratch on every request.

intermediate

How can you keep data between PHP requests if variables do not persist?

You can use sessions, cookies, databases, or files to save data between requests. These methods store data outside the script so it can be reused later.

intermediate

What is a session in PHP and how does it help with variable persistence?

A session stores data on the server linked to a user. It lets you save information like login status or preferences across multiple requests.

intermediate

Explain why PHP is called a 'stateless' language in the context of web requests.

PHP is stateless because it does not remember anything from one request to the next. Each request is independent, so variables do not persist unless you use special storage methods.

Why do PHP variables lose their values after a web request ends?

A Because variables are saved automatically

B Because PHP scripts start fresh on each request

C Because the browser deletes them

D Because the server crashes

PHP runs a new script for every request, so variables are reset each time.

Which method can you use to keep user data between PHP requests?

A Sessions

B Local variables

C Temporary variables

D Function parameters

Sessions store data on the server to keep it between requests.

What does it mean that PHP is 'stateless'?

A It runs only once

B It saves all variables automatically

C It stores data in the browser

D It does not remember data between requests

Stateless means no memory of previous requests unless you use storage like sessions.

When does PHP destroy all variables?

A At the end of each script execution

B When the user closes the browser

C After 1 hour

D When the server restarts

Variables exist only during the script run and are destroyed after it finishes.

Which of these is NOT a way to keep data between PHP requests?

A Using cookies

B Using sessions

C Using local variables

D Saving to a database

Local variables only exist during one script run and do not persist.

Explain in your own words why PHP variables do not keep their values between web requests.

Think about what happens each time you reload a web page.

Describe at least two ways to save data between PHP requests and why they are needed.

How can PHP remember information about a user across pages?

Practice

1. Why do PHP variables not keep their values between different page requests?

easy

A. Because PHP variables are saved only in cookies

B. Because PHP automatically deletes variables after 5 seconds

C. Because variables are stored only in the browser cache

D. Because each request starts a new script execution with fresh variables

Solution

1. Step 1: Understand PHP script execution

   Each time a PHP page loads, the server runs the script from the start with new variables.

2. Step 2: Recognize variable lifetime

   Variables exist only during that single script run and are lost after the page finishes loading.

3. Final Answer:

   Because each request starts a new script execution with fresh variables -> Option D

4. Quick Check:

   PHP variables reset each request = D [OK]

Hint: Remember: PHP runs fresh each page load, no memory kept [OK]

Common Mistakes:

• Thinking variables persist like JavaScript variables in browser
• Confusing PHP variables with cookies or sessions
• Assuming PHP stores variables on client side

2. Which of the following is the correct way to start a session in PHP to keep variables between requests?

easy

A. session_start();

B. start_session();

C. begin_session();

D. init_session();

Solution

1. Step 1: Recall PHP session function

   The correct function to start a session is session_start();.

2. Step 2: Verify syntax correctness

   Other options are not valid PHP functions and will cause errors.

3. Final Answer:

   session_start(); -> Option A

4. Quick Check:

   Use session_start() to begin sessions [OK]

Hint: Remember exact function name: session_start() [OK]

Common Mistakes:

• Using incorrect function names like start_session()
• Forgetting parentheses after function name
• Not calling session_start() before output

3. What will be the output of this PHP code on the second page load?

<?php
$counter = 0;
$counter++;
echo $counter;
?>

medium

A. 1

B. 2

C. 0

D. Error

Solution

1. Step 1: Analyze variable initialization

   Each page load sets $counter = 0;, so it resets every time.

2. Step 2: Increment and output

   Then $counter++ makes it 1, and echo prints 1.

3. Final Answer:

   1 -> Option A

4. Quick Check:

   Variable resets each load, so output is 1 [OK]

Hint: Variables reset each request unless stored externally [OK]

Common Mistakes:

• Assuming $counter keeps incrementing across requests
• Thinking output will be 2 or higher
• Expecting an error due to variable usage

4. This PHP code tries to keep a count between requests but always shows 1. What is the problem?

<?php
$counter = 0;
$counter++;
echo $counter;
?>

medium

A. The increment operator ++ is used incorrectly

B. The echo statement is missing a semicolon

C. Variables reset each request; no session or storage used

D. The variable $counter is not declared

Solution

1. Step 1: Identify variable reset issue

   The variable $counter is set to 0 on every request, so it never remembers previous value.

2. Step 2: Understand missing persistence method

   Without sessions or external storage, variables cannot keep values between requests.

3. Final Answer:

   Variables reset each request; no session or storage used -> Option C

4. Quick Check:

   Variables reset without session = B [OK]

Hint: Use sessions to keep variables between requests [OK]

Common Mistakes:

• Blaming increment operator for reset
• Thinking echo needs semicolon to work
• Assuming variable declaration is missing

5. You want to count how many times a user visits a page using PHP. Which approach correctly keeps the count between requests?

hard

A. Declare a global variable and increment it on each request

B. Use a session variable with session_start() and increment it

C. Use a local variable inside the script and increment it

D. Store the count in a variable inside the HTML code

Solution

1. Step 1: Understand variable lifetime

   Local and global PHP variables reset each request, so they can't keep count.

2. Step 2: Use sessions for persistence

   Sessions store data on the server between requests, so using session_start() and a session variable keeps count.

3. Final Answer:

   Use a session variable with session_start() and increment it -> Option B

4. Quick Check:

   Sessions keep data between requests = A [OK]

Hint: Use sessions to save data across page loads [OK]

Common Mistakes:

• Thinking global variables persist across requests
• Trying to store PHP variables in HTML
• Not starting session before using session variables