Print the keys of an array

You can use PHP’s array_keys function to grab the keys, like so:

foreach(array_keys($parameters) as $paramName)
  echo $paramName . "<br>";

Or, you can run through the array using a special foreach which allows you to separate the key and value for every element, like so:

foreach($parameters as $paramName => $value)
  echo $paramName . "<br>";

Also, make sure that you are using a "string" (with quotes) or integer (like 1337) as your key, like so:

$parameters["day"] = 1;
$parameters["month"] = 8;
$parameters["year"] = 2010;

OR if you want to get fancier:

$parameters = array(
  "day" => 1,
  "month" => 8,
  "year" => 2010
);

Your code should look like:

$parameters = array(
  "day" => 1,
  "month" => 8,
  "year" => 2010
);
foreach($parameters as $paramName => $paramValue)
  echo $paramName . "<br>";