detect endianness

[Jimmy Zhang]

Hi, I am wondering if C# always assumes small-endian byte order, if not,
how should I test the endianess of the platform, there doesn't seem to be a
way to check as pointers are implicit (as opposed to being explicit in C)?

Thanks
jz

[=?ISO-8859-1?Q?G=F6ran_Andersson?=]

Jimmy Zhang wrote:

Hi, I am wondering if C# always assumes small-endian byte order, if not,
how should I test the endianess of the platform, there doesn't seem to be a
way to check as pointers are implicit (as opposed to being explicit in C)?

Thanks
jz

Just read the first byte of a short or int with the value 1. If the byte
is 1, the memory model is little-endian.

My recollection of pointer syntax is a bit muddy, but something like
this would do it:

byte b;
unsafe {
int i = 1;
byte* bp = (byte*)&i;
b = *bp;
}

--
Göran Andersson
_____
http://www.guffa.com

[=?ISO-8859-1?Q?Arne_Vajh=F8j?=]

Jimmy Zhang wrote:

Hi, I am wondering if C# always assumes small-endian byte order, if not,
how should I test the endianess of the platform, there doesn't seem to be a
way to check as pointers are implicit (as opposed to being explicit in C)?

MS .NET only runs on little endian platforms

Mono runs on both little and big endian platforms.

For obvious performance reasons it uses the native
endianess internally, but that is completely transparent.

It is only relevant when you are exchanging data.

System.IO BinaryReader and BinaryWriter always
uses little endian.

System BitConverter uses actual system endianess.

BitConverter also has a static field IsLittleEndian
you can use to test for.

Arne

[Jon Skeet [C# MVP]]

Arne Vajhøj <ar**@vajhoej.dkwrote:

Jimmy Zhang wrote:

Hi, I am wondering if C# always assumes small-endian byte order, if not,
how should I test the endianess of the platform, there doesn't seem to be a
way to check as pointers are implicit (as opposed to being explicit in C)?

MS .NET only runs on little endian platforms

Mono runs on both little and big endian platforms.

For obvious performance reasons it uses the native
endianess internally, but that is completely transparent.

It is only relevant when you are exchanging data.

System.IO BinaryReader and BinaryWriter always
uses little endian.

System BitConverter uses actual system endianess.

BitConverter also has a static field IsLittleEndian
you can use to test for.

And in addition, if you want complete control, you can use my
EndianBitConvert and EndianBinaryReader/Writer classes:

http://www.pobox.com/~skeet/csharp/miscutil

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too