public void exporttoexcel(DataGridView grid)
        {   
Microsoft.Office.Interop.Excel.ApplicationClass excelSheet = new Microsoft.Office.Interop.Excel.ApplicationClass();
            excelSheet.Application.Workbooks.Add(true);
            int columnIndex = 0;
            //Columns Heading of Datagridview     
            foreach (DataGridViewColumn column in grid.Columns)
            {
                columnIndex++;
                excelSheet.Cells[1, columnIndex] = column.HeaderText;
            }
            int rowIndex = 0;
            //get all rows by column wise 
            foreach (DataGridViewRow row in grid.Rows)
            {
                rowIndex++;
                columnIndex = 0;
                foreach (DataGridViewColumn column in grid.Columns)
                {
                    columnIndex++;
                        excelSheet.Cells[rowIndex + 1, columnIndex] = row.Cells[column.Name].FormattedValue;
                }
            }
            excelSheet.Visible = true;
            Microsoft.Office.Interop.Excel.Worksheet workSheet = (Microsoft.Office.Interop.Excel.Worksheet)excelSheet.ActiveSheet;
            workSheet.Activate();
}