Read file.inputstream twice

Question

I need to read csv file twice. but after first reading:

using (var csvReader = new StreamReader(file.InputStream))
{
    fileFullText += csvReader.ReadToEnd();
    file.InputStream.Seek(0, SeekOrigin.Begin);
    csvReader.Close();
}

using file in enother function:

public static List<string> ParceCsv(HttpPostedFileBase file)
{
    //file.InputStream.Seek(0, SeekOrigin.Begin);
    using (var csvReader = new StreamReader(file.InputStream))
    {
       // csvReader.DiscardBufferedData();
       // csvReader.BaseStream.Seek(0, SeekOrigin.Begin);
        string inputLine = "";
        var values = new List<string>();

        while ((inputLine = csvReader.ReadLine()) != null)
        {
            values.Add(inputLine.Trim().Replace(",", "").Replace(" ", ""));
        }
        csvReader.Close();
        return values;
    } 
}

The file.Length is 0. Can anybody help?

Answer 1

The reason is that SteramReader's Dispose() method also closes the underlying stream; In your case file.InputStream. The using statement calls Dispose() implicitly. Try to replace using with disposes of both your StreamReaded-s after you finished both read operations. As I remember some stream classes have a bool option to leave underlying stream open after dispose.

.NET 4.5 fixed this issue by introducing leaveOpen parameter in SteamReader constructor. See: MSDN

public StreamReader(
    Stream stream,
    Encoding encoding,
    bool detectEncodingFromByteOrderMarks,
    int bufferSize,
    bool leaveOpen
)

One more thing. You do not need to close SteramReader yourself (the line with csvReader.Close();) when you wrap it in using statement, thus Dispose() and Close() are the same in case of StreamReader.