//全选
private void btnAllchoose_Click(object sender, EventArgs e)
        {
      for (int i = 0; i < dataGridView1.Rows.Count; i++)
            {
                dataGridView1.Rows[i].Cells[0].Value = true;
            }
}
//反选
private void btnRchose_Click(object sender, EventArgs e)
        {
            for (int i = 0; i < dataGridView1.Rows.Count; i++)
            {
                DataGridViewCheckBoxCell chk = (DataGridViewCheckBoxCell)dataGridView1.Rows[i].Cells[0];
                if ((Boolean)chk.EditedFormattedValue == true)
                {
                    dataGridView1.Rows[i].Cells[0].Value = false;
                }
                else
                    dataGridView1.Rows[i].Cells[0].Value = true;
            }

        }