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Convert.ToUInt64 Method (Int64)

Converts the value of the specified 64-bit signed integer to an equivalent 64-bit unsigned integer.

This API is not CLS-compliant. 

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

public static ulong ToUInt64(
	long value


Type: System.Int64

The 64-bit signed integer to convert.

Return Value

Type: System.UInt64
A 64-bit unsigned integer that is equivalent to value.


value is less than zero.

The following example attempts to convert each element in an array of long integers to an unsigned long integer.

long[] numbers = { Int64.MinValue, -19432, -18, 0, 121, 340, Int64.MaxValue };
ulong result;
foreach (long number in numbers)
   try {
      result = Convert.ToUInt64(number);
      Console.WriteLine("Converted the {0} value {1} to the {2} value {3}.",
                        number.GetType().Name, number,
                        result.GetType().Name, result);
   catch (OverflowException) {
      Console.WriteLine("The {0} value {1} is outside the range of the UInt64 type.",
                        number.GetType().Name, number);
// The example displays the following output: 
//    The Int64 value -9223372036854775808 is outside the range of the UInt64 type. 
//    The Int64 value -19432 is outside the range of the UInt64 type. 
//    The Int64 value -18 is outside the range of the UInt64 type. 
//    Converted the Int64 value 0 to the UInt64 value 0. 
//    Converted the Int64 value 121 to the UInt64 value 121. 
//    Converted the Int64 value 340 to the UInt64 value 340. 
//    Converted the Int64 value 9223372036854775807 to a UInt64 value 9223372036854775807.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0