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BitConverter::ToUInt64 Method

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

This API is not CLS-compliant. 

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

[CLSCompliantAttribute(false)]
public:
static unsigned long long ToUInt64(
	array<unsigned char>^ value, 
	int startIndex
)

Parameters

value
Type: array<System::Byte>

An array of bytes.

startIndex
Type: System::Int32

The starting position within value.

Return Value

Type: System::UInt64
A 64-bit unsigned integer formed by the eight bytes beginning at startIndex.

ExceptionCondition
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 nullptr.

ArgumentOutOfRangeException

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

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.

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

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

// Convert eight byte array elements to an unsigned __int64 value and  
// display it. 
void BAToUInt64( array<unsigned char>^bytes, int index )
{
   unsigned __int64 value = BitConverter::ToUInt64( bytes, index );
   Console::WriteLine( "{0,5}{1,27}{2,24}", index, BitConverter::ToString( bytes, index, 8 ), value );
}


// Display a byte array, using multiple lines if necessary. 
void WriteMultiLineByteArray( array<unsigned char>^bytes )
{
   const int rowSize = 20;
   int iter;
   Console::WriteLine( "initial unsigned char 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();
}

int main()
{
   array<unsigned char>^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( unsigned " 
   "char[ ], int ) \nmethod generates the following output. It " 
   "converts elements of a \nbyte array to unsigned __int64 " 
   "values.\n" );
   WriteMultiLineByteArray( byteArray );
   Console::WriteLine( "{0,5}{1,27}{2,24}", "index", "array elements", "unsigned __int64" );
   Console::WriteLine( "{0,5}{1,27}{2,24}", "-----", "--------------", "----------------" );

   // Convert byte array elements to unsigned __int64 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( unsigned char[ ], int )
method generates the following output. It converts elements of a
byte array to unsigned __int64 values.

initial unsigned char 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        unsigned __int64
-----             --------------        ----------------
    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
*/

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
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