Read/Write string binary data - BinaryReader

Question

I wrote the below method to archive files into one file using binary mode:

        // Compile archive
        public void CompileArchive(string FilePath, ListView FilesList, Label Status, ProgressBar Progress)
        {
            FileTemplate TempFile = new FileTemplate();
            if (FilesList.Items.Count > 0)
            {
                BinaryWriter Writer = new BinaryWriter(File.Open(FilePath, FileMode.Create), System.Text.Encoding.ASCII);
                Progress.Maximum = FilesList.Items.Count - 1;
                Writer.Write((long)FilesList.Items.Count);
                for (int i = 0; i <= FilesList.Items.Count - 1; i++)
                {
                    TempFile.Name = FilesList.Items[i].SubItems[1].Text;
                    TempFile.Path = "%ARCHIVE%";
                    TempFile.Data = this.ReadFileData(FilesList.Items[i].SubItems[2].Text + "\\" + TempFile.Name);
                    Writer.Write(TempFile.Name);
                    Writer.Write(TempFile.Path);
                    Writer.Write(TempFile.Data);
                    Status.Text = "Status: Writing '" + TempFile.Name + "'";
                    Progress.Value = i;
                }
                Writer.Close();
                Status.Text = "Status: None";
                Progress.Value = 0;
            }
        }

I read files data using ReadFileData which is in the above method method which return a string of data. (StreamReader) Next up I extract my archive. Everything is done great but the data which will being stored in the extraction method doesn't give me a right data so the extracted files have not right data to show their original functionality.

Extract method:

    // Extract archive
    public void ExtractArchive(string ArchivePath, string ExtractPath, ListView FilesList, Label Status, ProgressBar Progress)
    {
        FileTemplate TempFile = new FileTemplate();
        BinaryReader Reader = new BinaryReader(File.Open(ArchivePath, FileMode.Open), System.Text.Encoding.ASCII);
        long Count = Reader.ReadInt64();
        if (Count > 0)
        {
            Progress.Maximum = (int)Count - 1;
            FilesList.Items.Clear();
            for (int i = 0; i <= Count - 1; i++)
            {
                TempFile.Name = Reader.ReadString();
                TempFile.Path = Reader.ReadString();
                TempFile.Data = Reader.ReadString();
                Status.Text = "Status: Reading '" + TempFile.Name + "'";
                Progress.Value = i;
                if (!Directory.Exists(ExtractPath))
                {
                    Directory.CreateDirectory(ExtractPath);
                }
                BinaryWriter Writer = new BinaryWriter(File.Open(ExtractPath + "\\" + TempFile.Name, FileMode.Create), System.Text.Encoding.ASCII);
                Writer.Write(TempFile.Data);
                Writer.Close();
                string[] ItemArr = new string[] { i.ToString(), TempFile.Name, TempFile.Path };
                ListViewItem ListItem = new ListViewItem(ItemArr);
                FilesList.Items.Add(ListItem);
            }
            Reader.Close();
            Status.Text = "Status: None";
            Progress.Value = 0;
        }
    }

The structure:

struct FileTemplate
        {
            public string Name, Path, Data;
        }

Thanks.

In what way does the data get damaged? I.e:. You say it isn't right: what is different? Note: using ASCII will be very limiting. — Marc Gravell
– Marc Gravell, Commented Nov 19, 2011 at 18:46
No nothing get damage, I mean everything will be extracted well but e. g. when an icon is archived and when it is extracted the size and the name is correct but when I'm opening that Icon, it shows nothing to me. I got use to do this in VB6 even VB.Net but I don't how should I do this in here. — MahanGM
– MahanGM, Commented Nov 19, 2011 at 18:55
Off-Topic: instead of using Writer.Close() you can use using (BinaryWriter wr = new BinaryWriter(...)) { ... }, this cleans up the code a bit and you cannot use the BinaryWriter after closing the file. — Felix K.
– Felix K., Commented Nov 19, 2011 at 18:56

Felix K. · Accepted Answer · 2011-11-19 19:17:01Z

2

Consider using byte arrays for write and safe the data.

Byte array( write )

Byte[] bytes = File.ReadAllBytes(..);
// Write it into your stream
myStream.Write(bytes.Count);
myStream.Write(bytes, 0, bytes.Count);

Byte array ( read )

Int32 byteCount = myStream.ReadInt32();
Byte[] bytes = new Byte[byteCount];
myStream.Read(bytes, 0, byteCount);

edited Nov 19, 2011 at 19:17

answered Nov 19, 2011 at 19:03

Felix K.

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5 Comments

svick Over a year ago

How could you use File.WriteAllText() to write binary data?

Felix K. Over a year ago

If you read your file as text you could save it the same way.

svick Over a year ago

No, you can't. If you read binary file as text using some encoding, and then write it back, you most likely won't get the same bytes. Just don't treat binary data as text.

Felix K. Over a year ago

Made a quick test and you are right, never got this problem because i'm always using binary-data with byte arrays and not strings.

MahanGM Over a year ago

Thanks. I think this example is exactly the equivalence of what I was doing in vb6 (in the vb6's way not .net) :)

Marc Gravell · Accepted Answer · 2011-11-19 19:00:31Z

0

The example of an icon makes it clear; you are using string-based APIs to handle data that isn't strings (icons are not string-based). More, you are usig ASCII, so only characters in the 0-127 range would ever be correct. Basically, you can't do that. You need to handle binary data using binary methods (perhaps using the Stream API).

Other options:

use serialization to store instances of objects with the data properties and a BLOB (byte[]) for the content
use something like zip (maybe SharpZipLib) which does somethig very similar, essentially

answered Nov 19, 2011 at 19:00

Marc Gravell

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6 Comments

svick Over a year ago

I think the byte[] methods of BinaryReader/BinaryWriter should work too.

MahanGM Over a year ago

I think it's possible. I did it in VB.Net but with FileOpen and FileRead not Binary classes but they were in binary mode. So what's the difference? C# hasn't any method like the VB does.

svick Over a year ago

@MahanGM, C# has exactly the same methods as VB.Net.

Marc Gravell Over a year ago

@MahanGM if you use (from your code) ReadString to read something that isn't a string, then you've broken it. If you use ASCII to work with non-ASCII text, then you've broken it. You do both. It isn't a question of VB or not; the code as written is simply wrong

Marc Gravell Over a year ago

@svick see : .Data = Reader.ReadString() - it won't work if treated as a string

|

svick · Accepted Answer · 2011-11-19 19:01:31Z

0

If your Data can be binary data, then you shouldn't have them in a string. They should be a byte[].

When you write a string using the ASCII encoding like you do, and try to write binary data, many of the bytes (treated as Unicode characters) can't be encoded and so you end up with damaged data.

Morale of the story: never treat binary data as text.

answered Nov 19, 2011 at 19:01

svick

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1 Comment

MahanGM Over a year ago

As the matter of the fact, I got use to do this since my previous languages such as VB, they did this operation well. I don't know I should reconsider I think. Thanks.

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