Converting a big endian array to an Int64

Question

Im using a System.IO.BinaryReader to read a data from a serialized file. The file is big endian. So what I did to read the Int64 (long) from the stream was read 8 bytes from it. What I need to do is convert those 8 bytes of big endian into little endian long representation.

I can't use System.BitConverter as it will be compiled with Mono for use on Linux which could be running on big endian and with Visual Studio for Windows which is little endian.

What of it? Mono implements `System.BitConverter` as well – of course. — Konrad Rudolph, Apr 22 '12 at 23:18
I read [here](http://stackoverflow.com/a/2021679/1350209) that "BitConverter.ToInt64 is suppose to respect the endianness of your underlying machine." — Cole Tobin, Apr 22 '12 at 23:24
long value = Convert.ToInt64(binaryReader.ReadBytes(8).Reverse()); Skeet did something with big-endian, check his blog. — Hans Passant, Apr 22 '12 at 23:25

L.B · Accepted Answer · 2012-04-22T23:32:11.600

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You can use System.Net.IPAddress.NetworkToHostOrder or System.Net.IPAddress.HostToNetworkOrder

For ex, System.Net.IPAddress.HostToNetworkOrder(0x0123456789abcdefl) would return efcdab8967452301

edited Apr 22 '12 at 23:32

answered Apr 22 '12 at 23:26

L.B

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Don't forget that the machine you are on might be big endian in the first place. You can check by using BitConverter.IsLittleEndian http://msdn.microsoft.com/en-us/library/system.bitconverter.islittleendian.aspx . – Will Apr 23 '12 at 00:35

score 1 · Answer 2 · answered Apr 22 '12 at 23:55

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If you're going to end up using Mono anyway, you can use DataConvert.

Works fine on Windows too. I'm using it in one of my projects.

answered Apr 22 '12 at 23:55

mpen

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Even on regular .NET, I would say. DataConvert's Python/Perl-like pack/unpack functions are pleasure to use. – konrad.kruczynski Apr 24 '12 at 18:07

score 1 · Answer 3 · answered Apr 23 '12 at 00:34

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John Skeet's miscutil library implements a BigEndianBitConverter.

answered Apr 23 '12 at 00:34

spender

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I opened up his library and discovered he uses `Operator` in GenericMath. Never knew about this... I could have used it many times. Very cool! – mpen Apr 24 '12 at 19:57

Converting a big endian array to an Int64

3 Answers3