如何在datagridview中添加button按钮

//在datagridview中添加button按钮
            DataGridViewButtonColumn btn = new DataGridViewButtonColumn();
            btn.Name = "btnModify";
            btn.HeaderText = "修改";
            btn.DefaultCellStyle.NullValue = "修改";
            dataGridView1.Columns.Add(btn);  

private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
        {
            //点击button按钮事件
            if (dataGridView1.Columns[e.ColumnIndex].Name == "btnModify" && e.RowIndex >= 0)
            {
            //说明点击的列是DataGridViewButtonColumn列
                DataGridViewColumn column = dataGridView1.Columns[e.ColumnIndex];
                IPEntity ipentity = new IPEntity();
                ipentity.ipName = Convert.ToString(dataGridView1.CurrentRow.Cells[0].Value);
                ipentity.ipPart = Convert.ToString(dataGridView1.CurrentRow.Cells[1].Value);
                ipentity.ipStart = Convert.ToString(dataGridView1.CurrentRow.Cells[2].Value);
                ipentity.ipEnd = Convert.ToString(dataGridView1.CurrentRow.Cells[3].Value);
                bool flag = selectIp.UpdateIP(ipentity);
                if (flag)
                {
                    MessageBox.Show("更新成功！");
                }
                else
                {
                    MessageBox.Show("更新失败！");
                }
            }           
        }