how to create dynamically created $_POST vars?

acidbox

Usually, when I have to create a variable on the fly that was created from a FOR loop, I do it like the following:

${"user_id_" . $x}

This would in effect, create variables for as long as the for loop goes, in the format of:

$user_id_1
$user_id_2
$user_id_3
$user_id_4
$user_id_5

My problem is, I need to make sure that these variables are coming from a POSTED form, so I would like to somehow create this variable using the POST check, such as the following:

$_POST['user_id_1']

I cannot find the correct syntax to correctly combine the first example and the $_POST variable. I have tried many combinations of the two, and always receive the following message:

Parse error: parse error, expecting `']''

Does anyone know the syntax to create a dynamic variable that came from a $_POST ?

shawon22

in ur from use loop to create input boxes or hidden values and pass it to next page


<form action=test.php method=post>
?>
for($i=0; $i<5; $i++)
echo "<input name=" . $user_id_ . $i . " type=hidden>";

<input type=submit value=submit>
<?
</form>

acidbox

Ya, I know how to do that. That was not my question. My question was, how do you write the equivilant of this: ${"user_id" . $x} as a $POST[ ] variable so that it makes sure the variable came from a form as opposed to a URL passed variable.

acidbox

anyone have any insight on this topic? I really need to figure something out... thanks 😕

ednark

maybe playing with this will help

<?php

$mylist = isset($_GET['mylist']) ? $_GET['mylist'] : array( 'item_1'=>'', 'item_2'=>'', 'item_3'=>'', 'item_4'=>'' );

echo "<form action='{$PHP_SELF}' method='get'>\n";

foreach ( $mylist as $key=>$value ) {
    $value = htmlentities($value);
    print <<<EOINPUT
        mylist[{$key}] =&gt; <input type="input" name="mylist[{$key}]" value="{$value}" /><br />\n
EOINPUT;
}

echo "<br /><input type='submit'></form>\n";

echo "<br />\n";

for ( $i=1; $i<=count($mylist); $i++ ) {
    $key = "item_{$i}";
    $value = $_GET['mylist']["item_{$i}"];
    print "otherlist[{$key}] =&gt; {$value}<br />\n";
}

print "<br /><pre>\$mylist = ";
print_r($mylist);
print "</pre>";

?>

diego25

The $_POST array is an associative array, which means that the indices are strings. Therefore, to create an index, you can use concatenation, and any other string operator/function. e.g.

$POST["user_id" . $x]

Diego

acidbox

Diego, I tried that already, but I kept getting parse errors. In the meanwhile, I read somewhere that said you cannot construct variable variables from $_POST vars. That said, I think I will try to play around with the post that ednark posted. Thanks for the help.

diego25

Diego, I tried that already, but I kept getting parse errors.

Well, if you fix those parse errors, it should work. For example, this piece of code works:

<?
$_POST['user_id_1'] = '1';
$_POST['user_id_2'] = '2';
$_POST['user_id_3'] = '3';

for ($i = 1; $i <= 3; $i++) {
  print $_POST['user_id_' . $i] . "\n";
}

?>

Diego

Weedpacket

Any particular reason why you have to use variable variables?
Name the form fields name="user_id[1]", name="user_id[2]" etc. and then in the form refer to $POST['user_id'][1], $POST['user_id'][2], etc.

Much cleaner syntax.