PHP gets the header implementation steps for the http request

The PHP manual provides off-the-shelf functions:
getallheaders
(PHP 4, PHP 5)
getallheaders -- Fetch all HTTP request headers
instructions
array getallheaders ( void )
Fetches all HTTP headers from the current request.
This function is an alias for apache_request_headers(). Please read theapache_request_headers() documentation for more information on how this function works.
The return value
An associative array of all the HTTP headers in the current request, orFALSE on failure.
Example #1 getallheaders() example

 
<?php 
foreach (getallheaders() as $name => $value) { 
echo "$name: $value\n"; 
} 
?> 

However, this function can only be used in apache environment, iis or nginx does not support, can be implemented through custom functions

 
<?php 
<SPAN class=html>if (!function_exists('getallheaders')) 
{ 
&nbsp;&nbsp;&nbsp; function getallheaders() 
&nbsp;&nbsp;&nbsp; { 
&nbsp;&nbsp; &nbsp; &nbsp; foreach ($_SERVER as $name => $value) 
&nbsp;&nbsp; &nbsp; &nbsp; { 
&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (substr($name, 0, 5) == 'HTTP_') 
&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; { 
&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $headers[str_replace(' ', '-', ucwords(strtolower(str_replace('_', ' ', substr($name, 5)))))] = $value; 
&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; } 
&nbsp;&nbsp; &nbsp; &nbsp; } 
&nbsp;&nbsp; &nbsp; &nbsp; return $headers; 
&nbsp;&nbsp;&nbsp; } 
}</SPAN> 
?> 

Ok, so let's see what we get

 
<?php 
print_r(getallheaders()); 

Results obtained:

 
Array 
( 
[Accept] => */* 
[Accept-Language] => zh-cn 
[Accept-Encoding] => gzip, deflate 
[User-Agent] => Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; .NET CLR 2.0.50727) 
[Host] => localhost 
[Connection] => Keep-Alive 
)