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c#arraysbyteunsafe

Maximum length of byte[]?

I'm trying to create an array of bytes whose length is UInt32.MaxValue. This array is essentially a small(ish) in-memory database:

byte[] countryCodes = new byte[UInt32.MaxValue];

On my machine, however, at run-time, I get a System.OverflowException with "Arithmetic operation resulted in an overflow".

What's the deal? Do I need to use an unsafe block and malloc? How would I do that in C#?

Solution

  • The current implementation of System.Array uses Int32 for all its internal counters etc, so the theoretical maximum number of elements is Int32.MaxValue.

    There's also a 2GB max-size-per-object limit imposed by the Microsoft CLR.

    A good discussion and workaround here...

    And a few related, not-quite-duplicate, questions and answers here...