How can I increase php variable's value every time form is submitted?

Question

I have a variable in php, called $number, and I have a submit button:

<form method="get"><button type="submit" value="<?php echo $number; ?> name="next">Next</button></form>.

What I'd like to achieve, is to increase the value of that variable, by 10 for example, every time the form is submitted.

First this is how I'd tried it:

if(isset($_GET['next'])){
$number+=10;
}

But this code only increases its value once.

I've tried several methods that are not really worth mentioning, but none of them worked unfortunately.

Every time the form is submitted per user, or any user? Assuming the latter, you need to store the number in a data store, whether that's a file on the server, a database, or something else. — Jonnix, May 01 '19 at 12:11

Adam · Accepted Answer · 2019-05-01T12:22:45.800

2

<?php
session_start();
if(isset($_POST['next'])){
   $_SESSION['number'] += 10;
}
?>    
<form method="POST">
  <button type="submit" value="<?php echo $_SESSION['number']; ?>" name="next">
    Next
  </button>
</form>

POST the form, and use Sessions to ensure you still have the previous variable available after the reload.

Useful reading:

PHP Session: https://www.php.net/manual/en/reserved.variables.session.php

PHP Session Start: https://www.php.net/manual/en/function.session-start.php

According to Wikipedia:

GET requests a representation of the specified resource. Note that GET should not be used for operations that cause side-effects, such as using it for taking actions in web applications. One reason for this is that GET may be used arbitrarily by robots or crawlers, which should not need to consider the side effects that a request should cause.

and

POST submits data to be processed (e.g., from an HTML form) to the identified resource. The data is included in the body of the request. This may result in the creation of a new resource or the updates of existing resources or both.

edited May 01 '19 at 12:22

answered May 01 '19 at 12:14

Adam

1,294
11
24

Why change to POST? – Jonnix May 01 '19 at 12:16
As you are POSTing data, not GETing data. You are submitting data to be used: https://stackoverflow.com/questions/3477333/what-is-the-difference-between-post-and-get – Adam May 01 '19 at 12:17
But it's incorrect to use GET in this instance whether it would work or not. – Adam May 01 '19 at 12:18
But it's still incorrect and bad practice, so how about we encourage good practice yeah? – Adam May 01 '19 at 12:20
"POST submits data to be processed (e.g., from an HTML form)" ... I'm not the one who decides these things. – Adam May 01 '19 at 12:21
if(isset($_POST['next'])){ ... } <--- Data being processed. – Adam May 01 '19 at 12:23
Done with my pedantry :) – Jonnix May 01 '19 at 12:27

How can I increase php variable's value every time form is submitted?

1 Answers1