C# 4 and .NET 4

182 ❘ ChaPTer 7 OperAtOrs And cAsts
In fact, Console.WriteLine() has another overload that takes a double as a parameter and displays the
value of that double. If you look closely at the output from the first SimpleCurrency example, you will
find the very first line of output displayed Currency as a double, using this overload. In that example,
there wasn’t a direct cast from Currency to uint, so the compiler picked Currency-to-float-to-double
as its preferred way of matching up the available casts to the available Console.WriteLine() overloads.
However, now that there is a direct cast to uint available in SimpleCurrency2, the compiler has opted
for this route.
The upshot of this is that if you have a method call that takes several overloads, and you attempt to pass it a
parameter whose data type doesn’t match any of the overloads exactly, then you are forcing the compiler to
decide not only what casts to use to perform the data conversion, but which overload, and hence which data
conversion, to pick. The compiler always works logically and according to strict rules, but the results may
not be what you expected. If there is any doubt, you are better off specifying which cast to use explicitly.
summary
This chapter looked at the standard operators provided by C#, described the mechanics of object equality,
and examined how the compiler converts the standard data types from one to another. It also demonstrated
how you can implement custom operator support on your data types using operator overloads. Finally, this
chapter looked at a special type of operator overload, the cast operator, which allows you to specify how
instances of your types are converted to other data types.
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