read certain position in hexadecimal

[skkuan]

Hi C# experts
Said I have the following hexadecimal files
00000160h: 00 00 00 00 CD CD 00 30 39 21 03 50 00 02 0F 2E;
00000170h:
---

I need to read the bytes starting from CD.
I am not familiar with the offset buffer reading concept.
I tried to use this

byte[] buffer = new byte[52]; 
long addr = 5; (assuming I want to start to read from position 5
int count;
while ((count = stream.Read(buffer, addr, 52)) > 0) 

This doesn't work. Please help

Thanks in advance.

[GaryTexmo]

Well, buffer is just an array of bytes, so you should be able to access any valid index using the array index operator (ie, []). If you want to start at the first instance of CD you find, you should just be able to search through the buffer until you find it, then go from there. For example, some pseudo-code...

byte[] buffer = <declare buffer>
long start = find <value> in buffer
for (long i = start; i < buffer.Length; i++)
{
  // do something with buffer[i]
}

Does that help at all? I'm not sure about your stream.Read code... if the above doesn't help you I'll look further into it, I'm just a bit pressed for time and thought I could sneak in some help before I had to run :D

[tlhintoq]

00 00 00 00 CD CD 00 30 39 21 03 50 00 02 0F 2E;

By the way, your bolded CD is in array position 4, not 5. Arrays are zero indexed.

[0] = 00
[1] = 00
[2] = 00
[3] = 00
[4] = CD

Have you tried simply reading all the bytes, then when you have it all in memory take what you want from it? Don't worry about an offset while reading. Take it all, then filter out what you don't want.

[skkuan]

Thanks for the feedback. This gave me some ideas how to proceed.
I find the following works though.

 byte[] buffer = new byte[52]; 
 int count;
 int pos = 356;
 stream.Seek(pos, SeekOrigin.Begin);
 while ((count = stream.Read(buffer, 0, 52)) > 0) 
{}