c# stream writer ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

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2.33/5 (3 votes)

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Hi all ,
I am trying to read and write binary data from a .SYS file.I am accessing it as a binary file.I am supposed to replace at a specific position ( say : postion 4 to 35).while reading the particular data i used FileStream , its working fine.while writing , i have a problem ,, i am using filestream again ,, is there any function to replace only at a selected place. help me out.
thanks in advance
--- M.ARUN

Posted 14-Mar-11 0:26am

arunmj

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3 solutions

Solution 1

You can use Position property or Seek function.
For example:

C++

System.IO.FileStream fs = new System.IO.FileStream(handle, System.IO.FileAccess.ReadWrite);
            fs.Position = 35;
or
            fs.Seek(35, System.IO.SeekOrigin.Current);

I hope it helps.

Posted 14-Mar-11 0:32am

_Ares!!!

Updated 14-Mar-11 0:34am

v3

Comments

arunmj 14-Mar-11 6:42am

thanks for the timely help....can u tell me y is the Handle used .. it says the Handle is invalid....

_Ares!!! 14-Mar-11 6:51am

The FileStream has overloaded constructor.
Try this for example:
System.IO.FileStream fs = new System.IO.FileStream("C:\\file.bin", System.IO.FileAccess.ReadWrite);

_Ares!!! 14-Mar-11 6:58am

Firstly, You should read MSDN about FileStream class

arunmj 14-Mar-11 6:59am

which filemode shall i use ??? Filemode has append, create, createnew, open, opencreate ??

_Ares!!! 14-Mar-11 7:29am

As you need. If you want to open file only you should use open. But you should combine this with FileAccess.Read. Otherwise, if you want to write file use append or create with FileAccess.Write. See MSDN!!!

arunmj 14-Mar-11 7:41am

ya ,, i got it ,,,,

Sergey Alexandrovich Kryukov 14-Mar-11 14:00pm

Correct, my 5.
--SA

Solution 2

Use BinaryWriter from System.IO namespace which has a function Seek(). Using that you can select a position and then use the Write() function to write your variable type.

Posted 14-Mar-11 0:33am

Albin Abel

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OriginalGriff · Accepted Answer · 2011-03-14T00:38:00

Solution 3

Read the data from the file into a byte array. Change the bytes you want to. Write the file back.

I wouldn't bother with a stream for this!

C#

byte[] data = File.ReadAllBytes(@"F:\Temp\MyFile.sys");
data[4] = 0;
data[5] = 1;
...
File.WriteAllBytes(@"F:\Temp\MyFile.sys", data);

Posted 14-Mar-11 0:38am

OriginalGriff

Comments

Rajesh Anuhya 14-Mar-11 7:31am

Simple.., and Super +5

_Ares!!! 14-Mar-11 7:34am

Good low-level solution :)

arunmj 14-Mar-11 7:42am

but wat shall i do if i want to replace and array of bytes ???

OriginalGriff 14-Mar-11 7:47am

Use the Array.Copy method: http://msdn.microsoft.com/en-us/library/system.array.copy.aspx

Sergey Alexandrovich Kryukov 14-Mar-11 14:00pm

Griff, I basically agree, but it works only if the file is not too big.
If it is big, random access to file is not a problem but needs care programming... My 4 this time.
--SA