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in Technique[技术] by (71.8m points)

c# - Faster way of reading csv to grid

I have following in Windows Forms .NET 3.5

It works fine for csv with records less than 10,000 but is slower for records above 30,000. Input csv file can can any records between 1 - 1,00,000 records

Code currently used :

/// <summary>
        /// This will import file to the collection object
        /// </summary>
        private bool ImportFile()
        {
            try
            {

                String fName;
                String textLine = string.Empty;
                String[] splitLine;

                // clear the grid view

                accountsDataGridView.Rows.Clear();

                fName = openFileDialog1.FileName;

                if (System.IO.File.Exists(fName))
                {
                    System.IO.StreamReader objReader = new System.IO.StreamReader(fName);

                    do
                    {
                        textLine = objReader.ReadLine();
                        if (textLine != "")
                        {
                            splitLine = textLine.Split(',');
                            if (splitLine[0] != "" || splitLine[1] != "")
                            {
                                accountsDataGridView.Rows.Add(splitLine);
                            }
                        }
                    } while (objReader.Peek() != -1);
                }
                return true;
            }
            catch (Exception ex)
            {
                if (ex.Message.Contains("The process cannot access the file"))
                {
                    MessageBox.Show("The file you are importing is open.", "Import Account", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                }
                else
                {
                    MessageBox.Show(ex.Message);
                }

                return false;
            }

        }

Sample Input file :
18906,Y
18908,Y
18909,Y
18910,Y
18912,N
18913,N

Need some advice on optimizing this code for fast reads & view in grid.

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by (71.8m points)
List<string[]> rows = File.ReadAllLines("Path").Select(x => x.Split(',')).ToList();
DataTable dt = new DataTable();
dt.Columns.Add("1");
dt.Columns.Add("2");
rows.ForEach(x => {
  dt.Rows.Add(x);
});
dgv.DataSource = dt;

Try that, I suspected that you have some form of column names in the datagrid for now I just made them 1 and 2.

To filter as per your original code use:

List<string[]> rows = File.ReadAllines("Path").Select(x => x.Split(',')).Where(x => x[0] != "" && x[1] != "").ToList();

To get your columns from the DataGridView

  dt.Columns.AddRange(dgv.Columns.Cast<DataGridViewColumn>().Select(x => new DataColumn(x.Name)).ToArray());

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