BitConverter.ToUInt64 Method

Definition

Namespace:

System

Assemblies:

netstandard.dll, System.Runtime.dll

Overloads

ToUInt64(Byte[], Int32)	Returns a 64-bit unsigned integer converted from eight bytes at a specified position in a byte array.
ToUInt64(ReadOnlySpan<Byte>)	Converts bytes into an unsigned long.

ToUInt64(Byte[], Int32)

Source:

BitConverter.cs

Important

This API is not CLS-compliant.

Returns a 64-bit unsigned integer converted from eight bytes at a specified position in a byte array.

C#

[System.CLSCompliant(false)]
public static ulong ToUInt64(byte[] value, int startIndex);

Parameters

value

Byte[]

An array of bytes that includes the eight bytes to convert.

startIndex

Int32

The starting position within value.

Returns

UInt64

A 64-bit unsigned integer formed by the eight bytes beginning at startIndex.

Attributes

CLSCompliantAttribute

Exceptions

ArgumentException

startIndex is greater than or equal to the length of value minus 7, and is less than or equal to the length of value minus 1.

ArgumentNullException

value is null.

ArgumentOutOfRangeException

startIndex is less than zero or greater than the length of value minus 1.

Examples

The following code example converts elements of Byte arrays to UInt64 values with the ToUInt64 method.

C#

// Example of the BitConverter.ToUInt64 method.
using System;

class BytesToUInt64Demo
{
    const string formatter = "{0,5}{1,27}{2,24}";

    // Convert eight byte array elements to a ulong and display it.
    public static void BAToUInt64( byte[ ] bytes, int index )
    {
        ulong value = BitConverter.ToUInt64( bytes, index );

        Console.WriteLine( formatter, index,
            BitConverter.ToString( bytes, index, 8 ), value );
    }

    // Display a byte array, using multiple lines if necessary.
    public static void WriteMultiLineByteArray( byte[ ] bytes )
    {
        const int rowSize = 20;
        int iter;

        Console.WriteLine( "initial byte array" );
        Console.WriteLine( "------------------" );

        for( iter = 0; iter < bytes.Length - rowSize; iter += rowSize )
        {
            Console.Write(
                BitConverter.ToString( bytes, iter, rowSize ) );
            Console.WriteLine( "-" );
        }

        Console.WriteLine( BitConverter.ToString( bytes, iter ) );
        Console.WriteLine( );
    }

    public static void Main( )
    {
        byte[ ] byteArray = {
            255, 255, 255,   0,   0,   0,   0,   0,   0,   0,
              0,   1,   0,   0,   0, 100, 167, 179, 182, 224,
             13,   0, 202, 154,  59,   0,   0,   0,   0, 170,
            170, 170, 170, 170, 170,   0,   0, 232, 137,   4,
             35, 199, 138, 255, 255, 255, 255, 255, 255, 255,
            255, 127 };

        Console.WriteLine(
            "This example of the BitConverter.ToUInt64( byte[ ], " +
            "int ) \nmethod generates the following output. It " +
            "converts elements \nof a byte array to ulong values.\n" );

        WriteMultiLineByteArray( byteArray );

        Console.WriteLine( formatter, "index", "array elements",
            "ulong" );
        Console.WriteLine( formatter, "-----", "--------------",
            "------" );

        // Convert byte array elements to ulong values.
        BAToUInt64( byteArray, 3 );
        BAToUInt64( byteArray, 0 );
        BAToUInt64( byteArray, 21 );
        BAToUInt64( byteArray, 7 );
        BAToUInt64( byteArray, 29 );
        BAToUInt64( byteArray, 13 );
        BAToUInt64( byteArray, 35 );
        BAToUInt64( byteArray, 44 );
        BAToUInt64( byteArray, 43 );
    }
}

/*
This example of the BitConverter.ToUInt64( byte[ ], int )
method generates the following output. It converts elements
of a byte array to ulong values.

initial byte array
------------------
FF-FF-FF-00-00-00-00-00-00-00-00-01-00-00-00-64-A7-B3-B6-E0-
0D-00-CA-9A-3B-00-00-00-00-AA-AA-AA-AA-AA-AA-00-00-E8-89-04-
23-C7-8A-FF-FF-FF-FF-FF-FF-FF-FF-7F

index             array elements                   ulong
-----             --------------                  ------
    3    00-00-00-00-00-00-00-00                       0
    0    FF-FF-FF-00-00-00-00-00                16777215
   21    00-CA-9A-3B-00-00-00-00              1000000000
    7    00-00-00-00-01-00-00-00              4294967296
   29    AA-AA-AA-AA-AA-AA-00-00         187649984473770
   13    00-00-64-A7-B3-B6-E0-0D     1000000000000000000
   35    00-00-E8-89-04-23-C7-8A    10000000000000000000
   44    FF-FF-FF-FF-FF-FF-FF-7F     9223372036854775807
   43    FF-FF-FF-FF-FF-FF-FF-FF    18446744073709551615
*/

Remarks

The ToUInt64 method converts the bytes from index startIndex to startIndex + 7 to a UInt64 value. The order of bytes in the array must reflect the endianness of the computer system's architecture. For more information, see the Remarks section of the BitConverter class topic.

See also

• GetBytes(UInt64)

ToUInt64(ReadOnlySpan<Byte>)

Source:

BitConverter.cs

Important

This API is not CLS-compliant.

Converts bytes into an unsigned long.

C#

[System.CLSCompliant(false)]
public static ulong ToUInt64(ReadOnlySpan<byte> value);

Parameters

value

ReadOnlySpan<Byte>

A read-only span containing the bytes to convert.

Returns

UInt64

A 64-bit unsigned integer representing the converted bytes.

Attributes

CLSCompliantAttribute

Exceptions

ArgumentOutOfRangeException

The length of value is less than 8.