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Read File by blocks

Posted on 2011-02-20
Medium Priority
Last Modified: 2012-05-11
I want to read files by blocks.

I want to use it to compare files. This is to build a little Incremental Backup. I have to read the files by blocks.
Compare the values..

Or can anyone give me an example how to do it? Provide me with a better solution if it is possible.
Question by:databoks
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LVL 86

Accepted Solution

Mike Tomlinson earned 2000 total points
ID: 34939627
The standard FileStream allows you to read by blocks.  Just open it up, move the pointer with Seek(), then use Read().

In its simplest form:
Byte[] buffer = new Byte[4096];
            FileStream fs = new FileStream(@"c:\some\path to\a_file.ext", FileMode.Open);
            fs.Seek(someOffsetInBytes, SeekOrigin.Begin);
            fs.Read(buffer, 0, buffer.Length);

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LVL 29

Expert Comment

ID: 34939957
<< I want to use it to compare files.  >>

You may want to also look into hashing if you intend to compare files

Author Comment

ID: 34941868
Please give an example ny using gule streams
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LVL 86

Expert Comment

by:Mike Tomlinson
ID: 34943631
"gule streams"?...can you explain further?
LVL 16

Expert Comment

ID: 34943675
'gule' - perhaps a typo for 'file'? (F-G and U-I being adjacent)
LVL 86

Expert Comment

by:Mike Tomlinson
ID: 34943721
Hehe...good spot DansDanUK.  =)

Are you asking about comparing two files in blocks now?
...or how to do the Hashing as egl1044 suggests?

Do you need to know WHERE the two files differ?  (read by blocks)
...or just that they are different? (hashing is better)

Author Comment

ID: 34943742
Sorry - i meant using the FileStream Class., but i can see the example is there.

I have read this through my mobile but couldn't see the code example.

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