Assigning variables within a foreach loop?

[Schmoopy]

Hi there, I'm trying to assign variables dynamically through a foreach loop, where I want to assign the value of a variable in an array to its own variable, something like this:



$fields = array("name","time","where","phone_no","job_description","quoted_price");

foreach($fields as $field)
{
if(empty($_POST['{$field}']))
{
die("You need to complete all fields.");
}
else
{
$ . $field = $field;
}
}


Obviously this doesn't work but I'm curious to know how you could achieve it.

Like depending on the value in the array, assign that variable to itself. Of course I could get the same results in a different way but I like to make efficient code :)

I hope you can see what I mean...

Say "time" is being passed through:

$time = $field

Ok, well just ask me if you don't understand what I'm getting at.

Thanks,

Jack.

[Twey]

To start with, I'd just like to say that this (like just about every usage of variable variables) is very very bad and should not be done. If you find accessing your $_POST variables too much hard work, you have several options: you can rename the array ($s =& $_POST;) and access them that way ($s['name']); you can create a function (function s($s) { return $_POST[$s; } to access them (s('name');), which is nice because it allows you to insert a mysql_real_escape_string() or the like; if you don't need to access them as strings you can even cast the whole thing to an object ($s = (object) $_POST;)and access them them that way ($s->name).

That said, it is possible to do as you ask, and in fact there is a function to do it for you (extract (http://www.php.net/extract)()), although it doesn't provide the check (for safety reasons, make sure you pass EXTR_SKIP if the input is user-generated). Using your above code, and removing all the redundant braces, we get:


$fields = array('name',
'time',
'where',
'phone_no',
'job_description',
'quoted_price');

foreach ($fields as $field)
if (empty($_POST[$field]))
die('You need to complete all fields.');
else
$$field = $field;Note: we've used single quotes, not double quotes (double quotes provide interpolation, so they're slower; if you're not using interpolation, don't use them); we've replaced '{$field}', which is literal since it's in single quotes (if you'd put it in double quotes it would have been interpolated and worked as you expected, but it's redundant anyway) with $field; and we've used variable variable syntax $$name, where $name must be a string containing a valid variable name (http://b.lericson.se/~toxik/php_sucks_rant.log provides a basic introduction, as well as mentioning its foibles).

[Schmoopy]

Ok cheers for that, but still not getting what I wanted, using:



$fields = array('name');

foreach($fields as $field)
if(empty($_POST[$field]))
{
die('You need to complete all fields.');
}
else
{
echo $$field = $field;
echo $name;
}


I passed the value 'test' from the form on my other page to this one, and I wanted to end up with $name = 'test'. At the moment they're both echoing 'name', where did I go wrong?

[Twey]

Of course you are. You meant $_POST[$field] (and then you'll get them both echoing 'test', since (a = b) === b).

[Schmoopy]

Ah, yes of course :p

[Twey]

Er, that's $field, not 'field', sorry.