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UInt64 Structure

Represents a 64-bit unsigned integer.

The UInt64 type is not CLS-compliant. The CLS-compliant alternative type is Decimal. Int64 can be used when the original value is less than half of UInt64.MaxValue. For more information about CLS compliance, see What is the Common Language Specification.

For a list of all members of this type, see UInt64 Members.


[Visual Basic]
Public Structure UInt64
   Implements IComparable, IFormattable, IConvertible
public struct UInt64 : IComparable, IFormattable, IConvertible
public __value struct UInt64 : public IComparable, IFormattable,

[JScript] In JScript, you can use the structures in the .NET Framework, but you cannot define your own.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.


The UInt64 value type represents unsigned integers with values ranging from 0 to 18,446,744,073,709,551,615.

UInt64 provides methods to compare instances of this type, convert the value of an instance to its string representation, and convert the string representation of a number to an instance of this type.

CAUTION   Assigning a 64-bit value on a 32-bit Intel computer is not an atomic operation; that is, the operation is not thread safe. This means that if two people simultaneously assign a value to a static UInt64 field, the final value of the field cannot be predicted.

For information about how format specification codes control the string representation of value types, see Formatting Overview.

This type implements interfaces IComparable, IFormattable, and IConvertible. Use the Convert class for conversions instead of this type's explicit interface member implementation of IConvertible.


Namespace: System

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework

Assembly: Mscorlib (in Mscorlib.dll)

See Also

UInt64 Members | System Namespace | Int64