Geek Answers Handbook

Reading and writing very large text files in C #

I have a very large file with a size of almost 2 GB. I am trying to write a process to read a file and write it without the first line. To a large extent, I could only read and write one line at a time, which lasts forever. I can open it, delete the first line and save it faster in TextPad, although it is still very slow.

I use this code to get the number of entries in a file:

private long getNumRows(string strFileName)
{
    long lngNumRows = 0;
    string strMsg;

    try
    {
        lngNumRows = 0;
        using (var strReader = File.OpenText(@strFileName))
        {
            while (strReader.ReadLine() != null)
            {
                lngNumRows++;
            }

            strReader.Close();
            strReader.Dispose();
        }
    }
    catch (Exception excExcept)
    {
        strMsg = "The File could not be read: ";
        strMsg += excExcept.Message;
        System.Windows.MessageBox.Show(strMsg);
        //Console.WriteLine("Thee was an error reading the file: ");
        //Console.WriteLine(excExcept.Message);

        //Console.ReadLine();
    }

    return lngNumRows;
}

It only takes a few seconds. When I add the following code, it runs forever. Am I doing something wrong? Why does recording add so much time? Any ideas on how I can do this faster?

private void ProcessTextFiles(string strFileName)
{
    string strDataLine;
    string strFullOutputFileName;
    string strSubFileName;
    int intPos;
    long lngTotalRows = 0;
    long lngCurrNumRows = 0;
    long lngModNumber = 0;
    double dblProgress = 0;
    double dblProgressPct = 0;
    string strPrgFileName = "";
    string strOutName = "";
    string strMsg;
    long lngFileNumRows;

    try
    {
       using (StreamReader srStreamRdr = new StreamReader(strFileName))
        {
            while ((strDataLine = srStreamRdr.ReadLine()) != null)
            {
                lngCurrNumRows++;

                if (lngCurrNumRows > 1)
                {
                    WriteDataRow(strDataLine, strFullOutputFileName);
                }
            }

            srStreamRdr.Dispose();
        }
    }
    catch (Exception excExcept)
    {
        strMsg = "The File could not be read: ";
        strMsg += excExcept.Message;
        System.Windows.MessageBox.Show(strMsg);
        //Console.WriteLine("The File could not be read:");
        //Console.WriteLine(excExcept.Message);
    }
}

public void WriteDataRow(string strDataRow, string strFullFileName)
{
    //using (StreamWriter file = new StreamWriter(@strFullFileName, true, Encoding.GetEncoding("iso-8859-1")))
    using (StreamWriter file = new StreamWriter(@strFullFileName, true, System.Text.Encoding.UTF8))
    {
        file.WriteLine(strDataRow);
        file.Close();
    }
}
+4
source share
2

, , , , , , .

,

using (StreamWriter file = new StreamWriter(@strFullFileName, true, System.Text.Encoding.UTF8))
using (StreamReader srStreamRdr = new StreamReader(strFileName))
{
    while ((strDataLine = srStreamRdr.ReadLine()) != null)
    {
        lngCurrNumRows++;

        if (lngCurrNumRows > 1)
           file.WriteLine(strDataRow);
    }
}

lngCurrNumRow, while

strDataLine = srStreamRdr.ReadLine();
if(strDataLine != null)
{
    while ((strDataLine = srStreamRdr.ReadLine()) != null)
    {
           file.WriteLine(strDataRow);
    }
}
+7

. ( "D:\savegrp.log". 2 ). 6 ,

int counter = File.ReadAllLines(@"D:\savegrp.log").Length;
Console.WriteLine(counter);

.

File.WriteAllLines(@"D:\savegrp2.log",File.ReadAllLines(@"D:\savegrp.log").Skip(1));
Console.WriteLine("file saved");
0

More articles:


All Articles