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c#endiannessboxing

In C#, is boxing and unboxing involved when casting long to ulong and vice versa?

I know that boxing then unboxing is computationally expensive, and it happens when casting a value type to object or other reference type then back to value type. However, does this happen when I'm casting long to ulong or vice versa.

I have following code:

ulong number = (ulong)IPAddress.NetworkToHostOrder((long)BitConverter.ToUInt64(bytes));

My understanding is, since both long and ulong are value type, casting between them will not have any boxing or unboxing involved.

I just want to be sure, does the code above have boxing and unboxing involved?

Solution

  • ulong and long are both value types. Boxing only occurs if you convert a value type to a reference type.

    The source code for NetworkToHostOrder is here. As you can see, no boxing occurs there either; it's just bit operations.

    Some weirdness may occur if you use a checked conversion from ulong to long that is outside of the range of the long, because an exception object will be created. But you probably have larger problems at that point.