This may be old news for other people, but new to me and I am trying to put in new stuff that I learned. I wasn't aware of this, and after thinking about it, it does make sense (looking at it from how boxing/unboxing works), but I wished it had worked.
The following code will throw an InvalidCastException
| private void PassValue()
float f = 5;
double d = CastValue(f);
private double CastValue(object o)
return (o is float) ? (double)o : double.NaN;
So would the following.
private void PassValue()
int i = 5;
object o = i;
Int64 j = (Int64)o;
When .NET boxes a value type, it keeps the type with it, and any effort to cast it as something else will fail. I was surprised with this; a consumer of my infrastructure project was telling about this exception where a piece of code was casting an object passed as a double. He was passing a float.
Like I mentioned, after looking at it and thinking about it in terms of .NET boxing/unboxing, it makes sense. I just wished it had worked. I could've just used the Convert.ToDouble (or use IConvertible), but I wanted to make sure the passed value IS a numeric type. If it's a string, or a byte for instance, I want to throw an exception. Now I have to change my code so it checks for all possible numeric type and throw an exception if it's not. Bummer...