Member Avatar for Reliable

Although I've read about it it still doesn't sink in when you will need to pass in a variable. I think I know how i just don't know for what reason. If someone could provide that information for me i would appreciate it. Also, is PHP variable passing more efficient than doing so in HTML? Thanks for your time and help.

Edited by Reliable because: forgot something
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A simple way to think about variable passing is to separate scope from persistence. asked about moving data from page to page; covered the local scope case (function parameters) and showed one client-side transport. For short-lived, per-request values prefer explicit parameters or local variables to keep code testable. For state that must survive a redirect or multiple requests, choose between GET/POST, cookies, server-side sessions, or persistent storage (database) depending on sensitivity and lifetime.

Which method to use and why:

  • GET is for resource identifiers and bookmarkable filters; it is visible and modifiable by the user (see $_GET).
  • POST is for form submissions and larger payloads ( $_POST).
  • Sessions hold per-user server-side state without exposing values to the client (see sessions).
  • Cookies are small, client-side and persistent; do not store secrets (setcookie).
    Always treat client data as untrusted. Use filter_input and prepared statements, and regenerate session IDs after login with session_regenerate_id.

A minimal pattern for carrying transient state server-side:

<?php
session_start();
$_SESSION['flow_data'] = $_POST['step_value'] ?? null;
header('Location: next.php');
exit;
?>

Troubleshooting pointers: if a variable is missing, check the form method and name, ensure session_start() runs before output, call setcookie()/header() before any HTML, and always validate incoming values.

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Member Avatar for JRM

In what context are you referring?
Functions ?

function myFunction($var1, $var2){
return ($var1 + $var2);
}

In the example above I passed var1 and var2 into a function that adds them together and returns the result.

//call this function
$total =myFunction(1,2);

I passed 'hard coded' numbers here but variables could be used also

$a = 1;
$b =2;
$total =myFunction(a,b);

both will return 3 to $total

Edited by JRM because: n/a
Member Avatar for Reliable

In what context are you referring?
Functions ?

function myFunction($var1, $var2){
return ($var1 + $var2);
}

In the example above I passed var1 and var2 into a function that adds them together and returns the result.

//call this function
$total =myFunction(1,2);

I passed 'hard coded' numbers here but variables could be used also

$a = 1;
$b =2;
$total =myFunction(a,b);

both will return 3 to $total

I'm sorry. I should have been more clear. I meant from one page to another.

Member Avatar for Tekkno

So you are referring to something like this? <a href="whatever.com?variable=value">Example</a>

There are a lot of reasons, but the main reason I use them is to capture something specific in order to use it later. For example, say you've got a forum like daniweb. Each thread is essentially assigned an id to identify it. If a user is not logged in and tries to reply, they would be redirected to a login page first. But you need to keep track of the thread they were at. So you would pass a variable so the redirection script knows where they were initially to take them back there after log in. This is just one example of course.

Edited by Tekkno because: n/a
Member Avatar for Reliable

So you are referring to something like this? <a href="whatever.com?variable=value">Example</a>

There are a lot of reasons, but the main reason I use them is to capture something specific in order to use it later. For example, say you've got a forum like daniweb. Each thread is essentially assigned an id to identify it. If a user is not logged in and tries to reply, they would be redirected to a login page first. But you need to keep track of the thread they were at. So you would pass a variable so the redirection script knows where they were initially to take them back there after log in. This is just one example of course.

Nice example. I welcome others with a little code illustration. Thanks everyone.

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