C# Function to Calculate the Australian State from a Postcode

Many web forms and other systems ask for the postcode as well as the State. In Australia, it is a simple relationship and does not currently require a complex lookup table, since each State or Territory has a fixed numeric range of postcodes. By executing an IF-ELSE-ELSE-ELSE... one can easily determine the State. It also deals with the fact that most web forms will have data entered as strings, and attempts to parse it, or defaults to one of the States.