How to pass variable as $_POST key in PHP?

Question

How can you pass a variable as the $_POST array key value in PHP? Or is it not possible?

$test = "test";
echo $_POST[$test];

Thanks

Answer 1

If I get you right, you want to pass a variable from one php-file to another via post. This sure is possible in several ways.

1. With an HTML-form

<form action="target.php" method="post">
  <input type="text" name="key" value="foo" />
  <input type="submit" value="submit" />
</form>

if you click on the submit-button, $_POST['key'] in target.php will contain 'foo'.

2. Directly from PHP

$context = stream_context_create(array(
    'http' => array(
      'method'  => 'POST',
      'header'  => "Content-type: text/html\r\n",
      'content' => http_build_query(array('key' => 'foo'))
    ),
  ));
$return = file_get_contents('target.php', false, $context); 

Same thing as in 1., and $return will contain all the output produced by target.php.

3. Via AJAX (jQuery (JavaScript))

<script>
$.post('target.php', {key: 'foo'}, function(data) {
  alert(data);
});
</script>

Same thing as in 2., but now data contains the output from target.php.

Answer 2

$_POST['key'] = "foo";
echo $_POST['key'];

If I understood right, you want to set a $_POST key.