title: Object reference not set to an instance of an object IN c# export csv
body: <p>I designed a form to import and export into database then I used this code to export table into csv button</p>
  
  <p>but it always gives me that I have a problem inside the foreach "Object reference not set to an instance of an object"</p>
  
  <pre><code>        private void button5_Click(object sender, EventArgs e) 
      {
  //Build the CSV file data as a Comma separated string.
  string csv = string.Empty;
  
  //Add the Header row for CSV file.
  foreach (DataGridViewColumn column in dataGridView1.Columns)
  {
      csv += column.HeaderText + ',';
  }
  
  //Add new line.
  csv += "\r\n";
  
  //Adding the Rows
  foreach (DataGridViewRow row in dataGridView1.Rows)
  {
      foreach (DataGridViewCell cell in row.Cells)
      {
          //Add the Data rows.
          csv += cell.Value.ToString().Replace(",", ";") + ',';
      }
  
      //Add new line.
      csv += "\r\n";
  }
  
  //Exporting to CSV.
  string folderPath = "C:\\CSV\\";
  File.WriteAllText(folderPath + "DataGridViewExport.csv", csv);
  </code></pre>
  
  <p>}</p>