headers_list()

headers_list() — Returns a list of response headers sent (or ready to send).

Built-in function of PHP 8.5. The manual lists it as available in PHP 5, PHP 7, PHP 8. This page is the reference card: signature, parameters and return value, plus the changelog and the example the manual provides.

What it does

headers_list() will return a list of headers to be sent to the browser / client. To determine whether or not these headers have been sent yet, use headers_sent().

Signature

headers_list(): array

Parameters

This function takes no parameters.

Return value

Returns a numerically indexed array of headers.

Example

A runnable snippet:

/* setcookie() will add a response header on its own */ setcookie('foo', 'bar'); /* Define a custom response header This will be ignored by most clients */ header("Example-Test: foo"); /* Specify plain text content in our response */ header('Content-Type: text/plain; charset=UTF-8'); /* What headers are going to be sent? */ var_dump(headers_list());

Output:

array(3) { [0]=> string(19) "Set-Cookie: foo=bar" [1]=> string(17) "Example-Test: foo" [2]=> string(39) "Content-Type: text/plain; charset=UTF-8" }