#! code

Converting an IP address into some useful location information can be useful if you want to find out where sites are hosted or customise content to users depending on their location.

All this code is freely available over at github.

There are several ways to do this, all of which have their advantages and disadvantages, but sticking with one can cause rewriting a lot of code in the future. So rather than pick one and stick with it I decided to use dependency injection to allow different classes to be used that convert IP addresses to locations in different ways. The first task is to create an abstract class that will be used to construct the rest of the IP location classes. Each class that extends this abstract class will contain a method called getIpLocation() that will convert an IP address into a location, and a method that will update the data source for the location lookup. Rather than lump all of the classes into a single directory I have created a directory called Service, into which all of the different classes that lookup IP addresses will be kept.

There are two main ways in which to redirect the browser using JavaScript, both of which look at the location of the window object. These are the location.href property and location.replace function.

location.href

The following example will cause the page to redirect to another page, keeping the browser history. This might seem like a minor point, but if you redirect a user to another page they will be able to click back, which will mean that they are redirected again.

After installing PHP on Apache you can use the php.ini file to set various different options to do with PHP. When Apache starts it uses what is contained in this file to set up and run PHP.

On both Windows, Unix and Linux systems Apache will look in a number of default locations for the php.ini file before giving up. You can explicitly tell Apache 2.x where to look for the file by using the PHPIniDir directive in the http.conf file.

To redirect the current page to a different location you use the header() function in the following way:

header("http://www.hashbangcode.com");

You can use this function when you want to point the user to a different page. If you are writing a login script then this function would be useful to show the user a certain page depending on them entering the correct user information.