[code]<html>
<head>
<title>Velden vergeten</title>
<style type="text/css">
.forgotten {
	border: 1px solid #ff0000;
}
</style>
</head>
<body>
<?php
	//----- function to check required fields
	function CheckRequired($array)
	{
		//----- check if $array is not empty
		if (!empty($array))
		{
			//----- loop through the array and check if the value's been set
			foreach ($array as $value)
			{
				if (empty($_POST[$value]))
					$form_error[] = $value;
			}
		}
		
		//--- return an array with missed fields
		return $form_error;
	}
	
	//----- check for required fields
	if ($_SERVER['REQUEST_METHOD'] == 'POST')
		$required_fields = CheckRequired(array('name', 'email', 'message'));

	//----- check if all required fields are entered
	if ($_SERVER['REQUEST_METHOD'] == 'POST' && empty($required_fields))
	{
		echo 'Verwerk formulier';
	}
	else
	{
		//----- if form's been posted before, there are some fields left undone
		if (!empty($required_fields))
		{
			$i = 1;
			foreach ($required_fields as $value)
			{
				// echo 'U forgot the field: ' . ucfirst($value) . '.<br />';
				$varname = 'class_' . $value;
				${$varname} = 'class=forgotten';
					
				$i++;
			}
		}
		
		//----- start form
		echo "<form method=\"POST\" action=\"" . $_SERVER['PHP_SELF'] . "\">";
		echo "<p>";
		echo "<input type=\"text\" name=\"name\" value=\"" . htmlentities($_POST['name']) . "\" " . $class_name . " /> Name<br />";
		echo "<input type=\"text\" name=\"email\" value=\"" . htmlentities($_POST['email']) . "\" " . $class_email . " /> E-mail adres<br />";
		echo "<textarea name=\"message\" rows=\"8\" cols=\"\" style=\"width: 400px\" " . $class_message . ">" . htmlentities($_POST['message']) . "</textarea><br />";
		echo "<input type=\"submit\" name=\"submit\" value=\" Versturen \" />";
		echo "</p>";
		echo "</form>";
	}
?>
</body>
</html>[/code]