Why does my Http_build_url () function get an error?

Why does my Http_build_url () function get an error?
Echo Http_build_url ("Http:[email protected]/pub/index.php?a=b#files",
Array
"Scheme" = "ftp",
"Host" = "ftp.example.com",
"Path" = "files/current/",
"Query" = "A=c"
),
Http_url_strip_auth | Http_url_join_path | Http_url_join_query | Http_url_strip_fragment
);
?>
The manual is written without any configuration, direct use can, why my error fatal error:call to undefined function http_build_url () in E:\wamp\www\sometimeExa\bulid_ Url.php on line 2

------Solution--------------------
(PECL pecl_http >= 0.21.0)
------Solution--------------------
Http_build_url
(PECL pecl_http:0.21.0-1.5.5)

------Solution--------------------
http://pecl.php.net/*nix

Http://downloads.php.net/pierre/windows
------Solution--------------------
Http_build_url function is subordinate to pecl_http extension
PECL series extensions, not part of PHP's standard configuration family, are not maintained by the PHP development Organization
If there is no special need, do not use PECL extension as much as possible. If used, follow the developer's website closely to update and eliminate bugs

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