variable variables and arrays

[ansuz]

Hello all,

Say you have this defined in your html form:

<input name="someform[somefield]" value="someval">

How come in PHP this does not work:

$field_name = "someform[somefield]";
print ${$field_name};
// outputs blank

But on the other hand this works:

$form_name = "someform";
print ${$form_name}[somefield];
// outputs "someval

What the 😕 ???

In short, as soon as a variable name is referencing an array, the corresponding string cannot be used to reference another variable.

// won't work
$var_name = "array_name[field_name]";
print ${$var_name};

I am trying to understand for what fundamental reason it can't work and what are good workarounds for this?

Thanks for any info!

[swr]

There is a variable called someform with an element called somefield, but there is no variable called "someform[somefield]". I suppose there's no reason PHP couldn't interpret the square brackets in this context, but apparently it doesn't.

You could use [man]eval[/man] instead:

$someform = array('somefield' => 'foo');
$field_name = "someform[somefield]";
echo eval('return $'.$field_name.';');