reading file from begin

Question

1.00/5 (1 vote)

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hi
i am reading a file suppose that i am in line 9 i want return to line 1 again ?
is it good solution that i close file and open it again ??
it's text file

C#

 StreamReader Readfile = new StreamReader(@op.FileName.ToString());
 while ((Rline = Readfile.ReadLine()) != null)
                    {
                        temp = Rline;
                        temp = temp.Substring(1, 4).Replace(" ", string.Empty);
                        
                        if (Convert.ToInt32(temp) == Convert.ToInt32(textBox3.Text) && Convert.ToDateTime(Rline.Substring(6, 10)) >= InDate)
                        {
                            filewrite.WriteLine(Rline);
                        }
                    }
                progressBar1.Value = 20;
                Readfile.Close();
// here i want to read file again

Posted 29-Nov-12 9:19am

farham_heidari

Updated 29-Nov-12 10:00am

v7

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fjdiewornncalwe 29-Nov-12 15:24pm

Not enough information. Is this a text file, a binary file? How is your reader set up? Show us a code snippet of how you are reading from your file and we can provide more information.

2 solutions

Solution 1

You probably might use the Stream.Seek[^] method (you should check if your actual stream supports it, see the "Remarks" section in the linked page.

Posted 29-Nov-12 9:43am

CPallini

Comments

farham_heidari 29-Nov-12 15:50pm

i read the file one time i just want start again

lewax00 29-Nov-12 16:57pm

Then seek to 0. Did you read the page he linked to at all?

Sergey Alexandrovich Kryukov 29-Nov-12 18:00pm

Valid, my 5. But makes little to know sense in many cases, most likely, including OP's
Also, it should support Seek as it is a StreamReader over a file stream, as you can see.

Please see my answer -- also a couple of problems found...
--SA

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Sergey Alexandrovich Kryukov · Accepted Answer · 2012-11-29T11:58:00

In most cases, this is bad practice. You are only reading, so why would you ever come back? Remember result of the first line reading and go forward. Actually, if the file is not too big, you can gain a lot if you read everything at once and then only manipulate the string, using System.IO.StreamReader.ReadToEnd:
http://msdn.microsoft.com/en-us/library/system.io.streamreader.readtoend.aspx[^].

Now, a couple of notes:

Your FileName.ToString tells me a lot. What, don't you see that the file name is already a string?

Also, this is not a good pattern of using the types like StreamReader. It implements System.IDisposable, so you can use it via the using statement (not to be confused with using declaration):

C#

using (StreamReader reader = new StreamReader(@op.FileName.ToString())) {
    // use reader here
}   // here, reader.Dispose is automatically called; it will be closed,
    // the stream buffer won't be lost (especially important in case of StreamWriter)

Please see:
http://msdn.microsoft.com/en-us/library/system.idisposable.aspx[^],
http://msdn.microsoft.com/en-us/library/yh598w02%28v=vs.80%29.aspx[^].

—SA