Good morning, ask questions about the absolute path of PHP

Good morning, ask questions about the absolute path of PHP
Friends early, a new day the sun is diabolical ah.
Brother has a question to ask.
Define (' HOST ', ' http://'. $_server[' Http_host '). ' /');
I think that both local and server are using absolute paths, so the above is defined.
There is no problem on the server.
But locally, for example, mine is http://localhost/csdn/.
But the local echo HOST; it's just http://localhost/.
How can I write to achieve on the server and local is the same? That is, the local display of http://localhost/lcsdn/.
------to solve the idea----------------------
Put your program in the root directory, not under the Lcsdn folder
Which means your program is under the same level as LCSDN.
------to solve the idea----------------------
Set up as a virtual host
or by URL rewriting to assign the root of the site


It's not advisable to write a full URL.
------to solve the idea----------------------
$_server[' Http_host ' is to get the domain name or host address
Locally, you can also solve the problem by setting up a virtual host with Apache httpd.conf.

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