C# equivalent of 64-bit unsigned long long in C++

Question

I am building a DLL which will be used by C++ using COM. Please let me know what would be the C# equivalent of C++ 64-bit unsigned long long.

Will it be ulong type in C# ? Please confirm.

Thanks, Gagan

Nevillenevin

ulong is a 64-bit unsigned long int. – Matt

Answer 1

Maybe this will help you:

• ulong (64-bit unsigned integer)
• double(64-bit floating-point number).

Swindle

is that guaranteed for all time (like Java long type will always be 64 bit)? – Rampage

Huh? In C#, ulong is short for System.UInt64 which is (and always will be) a 64-bit unsigned integer. – Convulsion

@dtb: have you ever seen any official documentation with such guarantee about C# shorts? – Swindle

msdn.microsoft.com/en-us/library/ya5y69ds.aspx msdn.microsoft.com/en-us/library/exx3b86w.aspx msdn.microsoft.com/en-us/library/vstudio/ms228593.aspx – Convulsion

Answer 2

For anything that goes beyond ulong, you might as well use the C# BigInteger Structure.

Fixer

Finding factorial of numbers > 20 is not possible without BigInteger data type. Thanks for sharing. – Salter

not true anymore. Since .NET Core 7.0 you there are System.Int128 and System.UInt128 that's wider than ulong – Exobiology

Answer 3

In C++, the size of integer types varies depending on whether the program is running on a 32- or 64-bit machine, whereas C# integer types are platform-independent. So, they're not interoperable.

Rather, in C# there are the IntPtr and UIntPtr types, which are intended for P/Invoke, and whose size is 4 bytes on 32-bit machines and 8 bytes on 64-bit machines, which makes them equivalent to the C++ signed long and unsigned long types, respectively.

Pneumogastric

Answer 4

Since C++11, you can use these:

• int8_t
• int16_t
• int32_t
• int64_t
• uint8_t
• uint16_t
• uint32_t
• uint64_t

Their size is guaranteed to remain the same regardless of anything.

http://en.cppreference.com/w/cpp/types/integer.

Mcnutt

You got the question backwards – Discomfiture

Wrong way round, plus not very specific even if wanting to go into the DLL – Drillstock