Reading bytes from BigEndian

[TF]

Hi,
I've a byte array with 4 elements in BigEndian format i.e. {0, 0, 0,
12} and i want to convert it to 4-byte integer (Int32). I am trying
Encoding.BigEnd ianUnicode property but it has no effect on the result.
It always gives me number '201326592' instead of '12'.

Any help??

Here is the code:

Dim a_byte() As Byte = New Byte() {0, 0, 0, 12}

Dim ms As New MemoryStream(a_ byte)
Dim br As New BinaryReader(ms , Encoding.BigEnd ianUnicode)

Dim x As Int32 = br.ReadInt32() ' expecting x = 12

br.Close()
ms.Close()

[Jon Skeet [C# MVP]]

Re: Reading bytes from BigEndian

TF <faridt@coned.c om> wrote:[color=blue]
> I've a byte array with 4 elements in BigEndian format i.e. {0, 0, 0,
> 12} and i want to convert it to 4-byte integer (Int32). I am trying
> Encoding.BigEnd ianUnicode property but it has no effect on the result.
> It always gives me number '201326592' instead of '12'.[/color]

The Encoding is only used when you're reading strings. You can't change
the endianness of BinaryReader/Writer, unfortunately.

--
Jon Skeet - <skeet@pobox.co m>

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

If replying to the group, please do not mail me too

[ddinatal@troopers.state.ny.us]

Re: Reading bytes from BigEndian

That number is actually correct. Because it's BigEndian, then Encoding reverses your bytes into 12,0,0,0. COnverting this to binary = 00001100 00000000 00000000 00000000. If you do all the math, it comes out to 201326592. Below is a chart I made up quick in MS excel. If you add the 27th and 28th numbers (since these are set to 1 in the binary stuff above) you get 201326592. If you acutally want the number 12 to come out of your code, your byte array should look like: 12,0,0,0

1
2
4
8
16
32
64
128

256
512
1024
2048
4096
8192
16384
32768

65536
131072
262144
524288
1048576
2097152
4194304
8388608

16777216
33554432
67108864 (this one)
134217728 (and this one)
268435456
536870912
1073741824
2147483648


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[Jon Skeet [C# MVP]]

Re: Reading bytes from BigEndian

<Domenic (ddinatal@troop ers.state.ny.us )> wrote:[color=blue]
> That number is actually correct. Because it's BigEndian, then
> Encoding reverses your bytes into 12,0,0,0. COnverting this to binary
> = 00001100 00000000 00000000 00000000.[/color]

No, that would be little endianness. In little endianness, the least
significant byte is stored first, so 12 would be stored as {12, 0, 0,
0} - you'd reverse it to get {0, 0, 0, 12} or binary
00000000 00000000 00000000 00001100

See http://en.wikipedia.org/wiki/Endianness

The reason it's not working is because the encoding used by a
BinaryReader has nothing to do with calls to ReadInt32.

--
Jon Skeet - <skeet@pobox.co m>

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

If replying to the group, please do not mail me too