[C ＃ note] the data in DataGridView saved in WinForm is excel and CSV

Save as Excel

Use system.io preservation , Libraries that need to be imported ：using System.IO;

// Use system.io preservation 
//grid For the whole DataGridView object , and filePath For the path to save （ Include suffix ）, The same below 
public void saveExcelIO(DataGridView grid, string filePath)
{
    
    Thread.Sleep(1000);
    StreamWriter sw = new StreamWriter(filePath, false, Encoding.GetEncoding("gb2312"));
    StringBuilder sb = new StringBuilder();
    // Write the title 
    for(int k = 0; k < grid.Columns.Count; k++)
    {
    
        if (grid.Columns[k].Visible)
        {
    
            //\t It's equivalent to typing one on the keyboard tab key 
            sb.Append(grid.Columns[k].HeaderText.ToString().Trim() + "\t");
        }
    }
    // Line break 
    sb.Append(Environment.NewLine);
    // Start writing values for each line 
    for (int i = 0; i < grid.Rows.Count - 1; i++)
    {
    
        System.Windows.Forms.Application.DoEvents();
        for(int j = 0; j < grid.Columns.Count; j++)
        {
    
            if (grid.Columns[j].Visible)
            {
    
                // Cells have a certain number of bytes , May exceed , If it exceeds the limit, the contents of two cells will be the same 
                sb.Append(grid.Rows[i].Cells[j].Value.ToString().Trim() + "\t");
            }
        }
        sb.Append(Environment.NewLine);// Line break 
    }
    sw.Write(sb.ToString());
    sw.Flush();
    sw.Close();
}

Save as CSV

// preservation csv
public void saveCSV(DataGridView grid,string filePath)
{
    
    Thread.Sleep(1000);
    StreamWriter sw = new StreamWriter(filePath, false, Encoding.GetEncoding("gb2312"));
    string strLine = "";
    // Header 
    for (int i = 0; i < grid.ColumnCount; i++)
    {
    
        if (i > 0)
            strLine += ",";
        strLine += grid.Columns[i].HeaderText;
    }
    strLine.Remove(strLine.Length - 1);
    sw.WriteLine(strLine);
    strLine = "";
    for(int j = 0; j < grid.Rows.Count; j++)
    {
    
        strLine = "";
        int col = grid.Columns.Count;
        for(int k = 0; k < col; k++)
        {
    
            if (k > 0 && k < col)
                strLine += ",";
            if (grid.Rows[j].Cells[k].Value == null)
                strLine += "";
            else
            {
    
                string cell = grid.Rows[j].Cells[k].Value.ToString().Trim();
                // Prevent special symbols inside 
                cell = cell.Replace("\"", "\"\"");
                cell = "\"" + cell + "\"";
                strLine += cell;
            }
        }
        sw.WriteLine(strLine);
    }
    sw.Close();
}