SESSIONS: using a user input variable for multiple php pages [duplicate] - php

Question

This question already has answers here:
"Notice: Undefined variable", "Notice: Undefined index", "Warning: Undefined array key", and "Notice: Undefined offset" using PHP
(29 answers)
Closed 7 years ago.
I'm trying to study php and I'm already on the sessions part where I want to input something on my first page that would then be an output for the second page
1stpage.php
<?php session_start();?>
<form method="post">
Enter a number: <input type="number" name="num1" min="1" max="20" value="<?php echo $_SESSION["$num1"];?>">
<a href ="2ndpage.php">
<input type="button" name="select" value="select">
</a>
</form>
2ndpage.php
<?php
session_start();
echo $_SESSION[$num1];
?>
Well, it does'nt work and I'm getting lots of undefined index error. Any fix guys? Thanks in advance.

Answer 1

Take a look at form handling:
http://www.w3schools.com/php/php_forms.asp
If you still want to save the value into a session use:
$_SESSION['num1'] = $_POST['num1'];

Answer 2

1stpage.php
<?php session_start();?>
<?php if(isset($_SESSION['num1'])) $num1 = $_SESSION['num1']; else $num1 = ''; ?>
<form method="post" action="2ndpage.php">
Enter a number: <input type="number" name="num1" min="1" max="20" value="<?php echo $num1;?>">
<input type="submit" name="select" value="select">
</form>
2ndpage.php
<?php
session_start();
$_SESSION['num1'] = $_POST['num1'];
echo $_SESSION['num1'];
?>
What I have done here is I have first looked into the session if the num1 offset has been set into the session. If its not then I give $num as blank else I set the assign the value from session to $num.
Now when we input something and post it on 2nd page, the posted value is assigned to the variable in session and is displayed as well. So that next time you visit 1stpage.php while in same session, you will see your last posted value.
Let us know if it solves your practive problem or if this is not what you wanted.

Answer 3

I believe this is what you're trying to do:
Page 1:
<?php
session_start();
if(isset($_POST['select'])){
$num1 = $_POST['num1'];
$_SESSION['num1'] = $num1;
}
?>
<form method="post">
Enter a number: <input type="number" name="num1" min="1" max="20" value="<?php echo $_SESSION['num1']; ?>">
<input type="submit" name="select" value="select">
Click here to See the Value
</form>
Page 2:
<?php
session_start();
echo $_SESSION['num1'];
?>
Where, at first you press the select to enter the value inside
num1 then click on Click here to See the Value to see it.

Answer 4

I don't think you understand how all this works. You're having PHP output a session variable into a text box and expecting that that text box will somehow magically update your session. Somewhere you have to pass that data back to PHP and update it. So let's make your code into a process
<?php session_start(); ?>
<form method="post" action="process.php">
Enter a number: <input type="number" name="num1" min="1" max="20" value="<?php echo $_SESSION["$num1"];?>">
<input type="submit" name="select" value="select">
</form>
What I've done is make this form do a basic POST. If you want to avoid this you can use AJAX instead (same result using JS instead of HTML)
Next, let's make a basic process.php intermediate page
<?php
session_start();
$_SESSION['num1'] = (int)$_POST['num1'];
header('Location: 2ndpage.php');
Now we have a logistics chain for the data. You accept the data in your HTML and POST it to this page. It then takes it, sanitizes it (note I cast it to an (int) so we are certain this is a number) and then issues a redirect to the browser which takes you to your original landing page, which should now work.
This is all oversimplified for the process of teaching. You could have your form submit directly to 2ndpage.php and process there. Or, as I said before, you could use AJAX to send to process.php and when it returns some success parameter you then use JS to redirect. You have many options here.

Answer 5

Put this on the first page:
$_SESSION['num1'] = $num1;
and this on the second
$num1 = $_SESSION['num1'];