It's not "PHP" - that's the language being used. XAMPP usually uses Apache for it's web server, and it's the web server that determines the port.
Look for http.conf
. Edit it, and change the port to "80". Here are more details:
How to change XAMPP apache server port?
I believe you might also be able to use "xampp.ini":
Busy... Apache started [Port 80]
===============================================
ADDENDUM:
I don't thnk you understand.
There's ALWAYS a "port".
If you don't specify the port, it defaults to "80" (for http) or "443" (for https).
EXAMPLES:
http://localhost:8080/index.php: you're explicitly saying "index.php" and "port 8080".
http://localhost/index.php: port 80 is implicit.
http://localhost:80/index.php: port 80 is explicit. Examples 2) and 3) are EQUIVALENT. And finally,
http://localhost implies a) port 80, and b) index-dot-something: index.html
, index.htm
, index.php
, index.jsp
, etc. - whatever you've configured as a "default page".
'Hope that helps...