how to include a css-hidden input field in forms

I want to include a css-hidden input field in forms and check if the hidden f开发者_开发知识库ield has it’s value filled out then reject the submission

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Brief tutorial: Fighting Spam with CSS

A more comprehensive article on the subject: Stopping spambots with hashes and honeypots

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You may try something like this:

if (isset($_POST['submit']) && strlen($_POST['hidden_field']))
{
  // proceed with submission
}
else
{
  // reject because hidden field does not contain any value.
}