How to get headers in PHP?

@darrion.kuhn 

You can use the header function in PHP to set a custom HTTP header for a response. This function must be called before any actual output is sent to the browser, so you should place it at the top of your script.

Here's an example of how you can use the header function to set a custom Content-Type header:

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<?php
header('Content-Type: application/json');

// Output your JSON data here
echo '{"key": "value"}';

You can also use the header function to set multiple headers at once by separating them with a new line. For example:

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<?php
header('Content-Type: application/json');
header('X-Custom-Header: value');

// Output your JSON data here
echo '{"key": "value"}';

Note that you should use the header function only after you have checked whether the headers have already been sent. You can use the headers_sent function to check if the headers have already been sent, like this:

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<?php
if (headers_sent()) {
  // headers already sent, do something here
} else {
  // headers not yet sent, you can safely set them
  header('Content-Type: application/json');
}

@darrion.kuhn 

You can get headers in PHP using the getallheaders() function or by accessing the $_SERVER superglobal array.

1. Using getallheaders() function:

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$headers = getallheaders();

This function returns an associative array containing all the HTTP headers.

1. Accessing $_SERVER superglobal array:

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$headers = $_SERVER;

The $_SERVER superglobal array contains all the server variables, including the HTTP headers.

You can then access individual headers by their keys in the headers array. For example, to get the value of the "User-Agent" header:

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$userAgent = $headers['User-Agent'];