How to convert a byte array to a singe integer

[Star]

Hi all,

Let's suppose we have this:

byte[] buffer = new byte[3];

buffer[0] = 0x04;
buffer[1] = 0xF1;
buffer[2] = 0xB4;

int Res;


'Res' needs to be the concatenation of all those bytes.
I mean, it should be something like

Res = 0x04F1B4

which converted to integer is 324020.

On the other hand, buffer can contain any number of bytes,not only 3
(I know the length)


I tried
Res = Int32.Parse(buffer[0].ToString() + buffer[1].ToString() +
buffer[2].ToString());

but obviously it doesn't work

Any ideas?

Thanks!

 

[Jon Skeet [C# MVP]]

Let's suppose we have this:

byte[] buffer = new byte[3];

buffer[0] = 0x04;
buffer[1] = 0xF1;
buffer[2] = 0xB4;

int Res;


'Res' needs to be the concatenation of all those bytes.
I mean, it should be something like

Res = 0x04F1B4

which converted to integer is 324020.

<snip>

I don't know of anything which will work with arbitrary numbers of
bytes, but BitConverter is usually used for converting between bytes
and other types such as ints etc. However, you need 4 bytes to convert
to an int, 8 to convert to a long etc. Still, without knowing your real
use case, it might be useful.

(If the endianness is a problem, I have a version which allows you to
specify the endianness - see http://pobox.com/~skeet/csharp/miscutil)

 

[Peter Duniho]

[...]
'Res' needs to be the concatenation of all those bytes.
I mean, it should be something like

Res = 0x04F1B4

which converted to integer is 324020.

On the other hand, buffer can contain any number of bytes,not only 3
(I know the length)

Pedantic mode: obviously the buffer cannot contain *any* number of bytes..
It has to be within the range of the number of bytes used to represent the
destination type.

Anyway, that said, as an example of how you might use the BitConverter
class that Jon mentioned:

static public int Convert(byte[] rgbInput)
{
byte[] rgbWork = new byte[4];

if (rgbInput.Length > rgbWork.Length)
{
throw new ArgumentOutOfRangeException("Maximum length of
rgbInput is " + rgbWork.Length);
}

rgbInput.CopyTo(rgbWork, 0);

return BitConverter.ToInt32(rgbWork, 0);
}

Note that the code assumes your destination type is in fact an int, and
that the data is little-endian. The example you gave actually shows
big-endian data. To handle big-endian, you might add this line just
before the one calling the CopyTo() method:

Array.Reverse(rgbInput);

Hope that helps.

Pete

 

[Star]

Thanks for your replies.

Yes, BitConverter should work for me if I have 2, 4 or 8 bytes.
However, what should I call if I have 3 bytes?

 

[Peter Duniho]

Thanks for your replies.

Yes, BitConverter should work for me if I have 2, 4 or 8 bytes.
However, what should I call if I have 3 bytes?

Did you look at the code example I posted? You can pass an array of any
length, up the maximum length of the destination type. Including "3
bytes" for an int.

 

[Star]

oh, sorry about that, Peter!

I'll take a look. Thanks