Export to excel from Grid

private void button1_Click_1(object sender, EventArgs e)
        {
 
            // creating Excel Application
            Microsoft.Office.Interop.Excel._Application app  = new Microsoft.Office.Interop.Excel.Application();
 
 
            // creating new WorkBook within Excel application
            Microsoft.Office.Interop.Excel._Workbook workbook =  app.Workbooks.Add(Type.Missing);
           
 
            // creating new Excelsheet in workbook
             Microsoft.Office.Interop.Excel._Worksheet worksheet = null;                   
           
           // see the excel sheet behind the program
            app.Visible = true;
          
           // get the reference of first sheet. By default its name is Sheet1.
           // store its reference to worksheet
            worksheet = workbook.Sheets["Sheet1"];
            worksheet = workbook.ActiveSheet;
 
            // changing the name of active sheet
            worksheet.Name = "Exported from gridview";
 
           
            // storing header part in Excel
            for(int i=1;i<datagridview1.columns.count+1;i++)>
            {
    worksheet.Cells[1, i] = dataGridView1.Columns[i-1].HeaderText;
            }
 
 
 
            // storing Each row and column value to excel sheet
            for (int i=0; i < dataGridView1.Rows.Count-1 ; i++)
            {
                for(int j=0;j<datagridview1.columns.count;j++)>
                {
                    worksheet.Cells[i + 2, j + 1] = dataGridView1.Rows[i].Cells[j].Value.ToString();
                }
            }
 
 
            // save the application
            workbook.SaveAs("c:\\output.xls",Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing,Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlExclusive , Type.Missing, Type.Missing, Type.Missing, Type.Missing);
           
            // Exit from the application
          app.Quit();
        }
 
   
Note this part of code gets data from DataGridView and fills cells.

            // storing Each row and column value to excel sheet
            for (int i=0; i < dataGridView1.Rows.Count-1 ; i++)
            {
                for(int j=0;j<datagridview1.columns.count;j++)>
                {
                    worksheet.Cells[i + 2, j + 1] = dataGridView1.Rows[i].Cells[j].Value.ToString();
                }
            }