What is the maximum length of an array in .NET on 64-bit Windows

by

An array could theoretically have at most 2,147,483,647 elements, since it uses an int for indexing. The actual limit is slightly lower than this, depending on the type contained within the array.

However, there is a 2GB maximum single object restriction in the .NET CLR, even in 64bit. This was done by design.

You can easily make an IList<T> implementation that, internally, keeps multiple arrays, and allows you to grow beyond the 2GB single object limit, but there is not one in the framework itself.

Typically, however, this is not a real problem. Most of the time, you’ll have arrays pointing to large classes – so the array is just holding references. This would mean your array can effectively point to many, many GBs of memory – but the array itself cannot be >2GB.

Note that, as of .NET 4.5, there is a new option available where 64bit applications can opt-in: gcAllowVeryLargeObjects. With this new option set, it is possible to get UInt32.MaxValue (4,294,967,295) elements in a multi-dimensional array, though a single dimensional array is still limited to 2,146,435,071 elements (2,147,483,591 for single byte arrays or arrays of a struct containing nothing ut a byte).

The new rules with this option are:

  • The maximum number of elements in an array is UInt32.MaxValue.
  • The maximum index in any single dimension is 2,147,483,591 (0x7FFFFFC7) for byte arrays and arrays of single-byte structures, and 2,146,435,071 (0X7FEFFFFF) for other types.
  • The maximum size for strings and other non-array objects is unchanged.

More Related Contents:

  1. Array versus List: When to use which?
  2. Why are multi-dimensional arrays in .NET slower than normal arrays?
  3. Performance of Arrays vs. Lists
  4. Array.Copy vs Buffer.BlockCopy
  5. What is the difference between Dim v As String() and Dim v() As String?
  6. Memory layout of a .NET array
  7. Shuffling an array of strings in vb.net
  8. Upload files with HTTPWebrequest (multipart/form-data)
  9. Like Operator in Entity Framework?
  10. LINQ to SQL Left Outer Join
  11. Why Large Object Heap and why do we care?
  12. printing all contents of array in C#
  13. Running .net based application without .NET Framework
  14. How do I convert struct System.Byte byte[] to a System.IO.Stream object in C#?
  15. What is the best implementation for AOP in .Net? [closed]
  16. How do I set a ViewModel on a window in XAML using DataContext property?
  17. Change WPF DataTemplate for ListBox item if selected
  18. Update primary key value using entity framework
  19. How to programmatically derive Windows Downloads folder “%USERPROFILE%/Downloads”?
  20. How can I force .NET to use a local copy of an assembly that’s in the GAC
  21. Control.ResolveUrl versus Control.ResolveClientUrl versus VirtualPathUtility.ToAbsolute
  22. Organizationally, where should I put common queries when using Entity Framework Code First?
  23. How can I avoid SQL injection attacks in my ASP.NET application?
  24. Are there any better ways to copy a native dll to the bin folder?
  25. Determine if a generic param is a Nullable type
  26. How can I represent a very large integer in .NET?
  27. Get the name of Enum value
  28. What is a .snk for?
  29. What’s the best way to automate secure FTP in PowerShell?
  30. Is project.json deprecated?

Leave a Comment