only thing you have to do is change

httpd.conf

Listen 80 to 8080

ServerName : localhost:80 to 8080

and

C:\xampp\apache\conf\extra

httpd-ssl.conf

Listen 443 to 4499

and

VirtualHost default:443 to 4499

ServerName www.example.com:443 to 4499

Source

Stackoverflow.com