Using generated php variable as name for html <input> object in loop

Question

On the first page (index.php) I wrote this:

<?php   
echo '<form action="test.php" method="get">';
$x=0;
while($x<5){
$x++;
$test='tester'.$x;
echo '<input type="text" name="$test"><br>';
};
echo '<input type="submit" value="submit">';
?>

on the second page (test.php) I wrote this:

<?php 
echo $_POST['tester1'];
echo $_POST['tester2'];
echo $_POST['tester3'];
echo $_POST['tester4'];
echo $_POST['tester5'];
?>

and when I tested it I got these errors

Notice: Undefined index: tester1 in C:\xampp\htdocs\test.php on line 2

Notice: Undefined index: tester2 in C:\xampp\htdocs\test.php on line 3

Notice: Undefined index: tester3 in C:\xampp\htdocs\test.php on line 4

Notice: Undefined index: tester4 in C:\xampp\htdocs\test.php on line 5

Notice: Undefined index: tester5 in C:\xampp\htdocs\test.php on line 6

The code below is an example for the real code being meant for users to fill in a number. I want to use these numbers later for calculations so they all need an unique name. The <input> objects are generated via a loop, the amount of times the loop runs is specified by the amount of rows in a database.

In single-quotes, PHP variables are not passed as variables, but the actual text will be output. It should look like echo '<input type="text" name="'.$test.'"><br>'; — Qirel
– Qirel, Commented Feb 2, 2016 at 14:26
You also have method="get", so they are passed in the URL instead over POST. Change it to method="POST". Apply both changes of what I commented, that should work. — Qirel
– Qirel, Commented Feb 2, 2016 at 14:31
like what @Qirel said, these are correction you need to make, on top of it, i hope you didn't miss out your closing form tag. — Mark Ng
– Mark Ng, Commented Feb 2, 2016 at 14:37

Qirel · Accepted Answer · 2016-02-02 14:43:53Z

The two main issues are that you are using PHP variables inside single quotes, this doesn't pass the actual variable, but the actual name. As an example

$foo = "bar";
echo 'This is $foo';

would print

This is $foo

If you use double-quotes, the variable's content would be passed,

$foo = "bar";
echo "This is $foo"; // You can also do the following: echo 'This is '.$foo;

would print

This is bar

Secondly, you are using method="get" in your form, but trying to retrieve them as POST variables. This means that you have to change it to method="POST".

Another alternative, is to create an array of elements, and use a loop in PHP to retrieve the values. An example given below. The first snippet generates a form with 5 input-fields as an array.

<form action="test.php" method="POST">
    <?php for ($x=0; $x<5; $x++) { ?>
    <input type="text" name="tester[]" />
    <?php } ?>
    <input type="submit" name="submit" />
</form>

And in PHP, loop through that array.

<?php
if (isset($_POST['tester']) {
    // If the values are set, to avoid Undefined Index notices
    foreach ($_POST['tester'] as $value) {
        echo $value."<br />";
    }
}
?>

hherger · Accepted Answer · 2016-02-02 14:33:15Z

0

This is how it works (index.php):

<?php
    echo '<form action="test.php" method="post">';
    $x=0;
    while($x<5){
        $x++;
        $test='tester'.$x;
        echo '<input type="text" name="'.$test.'"><br>';
    };
    echo '<input type="submit" value="submit">';
?>

edited Feb 2, 2016 at 14:33

answered Feb 2, 2016 at 14:31

hherger

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2 Comments

Qirel Over a year ago

Can't use method="get" when trying to retrieve them as POST in PHP.

Sander Herreman Over a year ago

yeah its because i had tried it with method get and post and I didnt change it right when i posted the question

Jake Psimos · Accepted Answer · 2016-02-02 14:38:39Z

0

simply append this code to the top of test.php

if(!isset($_POST['tester1']) || !isset($_POST['tester2']) ... etc){
     exit(0); //or do something to signal index.php of missing values
}
/* (the rest of the code */

When writing a dynamic page like this, you should always expect there to be a missing variable and code an escape so you never run into an error such as that.

answered Feb 2, 2016 at 14:38

Jake Psimos

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