HEADER_REGISTER_CALLBACK(3) 1 HEADER_REGISTER_CALLBACK(3)
header_register_callback - Call a header function
SYNOPSIS
bool header_register_callback (callable $callback)
DESCRIPTION
Registers a function that will be called when PHP starts sending output.
The $callback is executed just after PHP prepares all headers to be sent, and before any other output is sent, creating a window to manip-
ulate the outgoing headers before being sent.
PARAMETERS
o $callback
- Function called just before the headers are sent. It gets no parameters and the return value is ignored.
RETURN VALUES
Returns TRUE on success or FALSE on failure.
EXAMPLES
Example #1
header_register_callback(3) example
<?php
header('Content-Type: text/plain');
header('X-Test: foo');
function foo() {
foreach (headers_list() as $header) {
if (strpos($header, 'X-Powered-By:') !== false) {
header_remove('X-Powered-By');
}
header_remove('X-Test');
}
}
$result = header_register_callback('foo');
echo "a";
?>
The above example will output something similar to:
Content-Type: text/plain
a
NOTES
header_register_callback(3) is executed just as the headers are about to be sent out, so any output from this function can break output.
Note
Headers will only be accessible and output when a SAPI that supports them is in use.
SEE ALSO
headers_list(3), header_remove(3), header(3).
PHP Documentation Group HEADER_REGISTER_CALLBACK(3)
