一：DatagridviewComboBox 选定索引更改时更改 DatagridviewTextBox 文本内容

 private void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
    {
        if (dataGridView1.CurrentCell.ColumnIndex == 1 && e.Control is ComboBox)
        {
            ComboBox comboBox = e.Control as ComboBox;
            comboBox.SelectedIndexChanged += LastColumnComboSelectionChanged;
        }
    }

    private void LastColumnComboSelectionChanged(object sender, EventArgs e)
    {
        var currentcell = dataGridView1.CurrentCellAddress;
        var sendingCB = sender as DataGridViewComboBoxEditingControl;
        DataGridViewTextBoxCell cel = (DataGridViewTextBoxCell)dataGridView1.Rows[currentcell.Y].Cells[0];
        cel.Value = sendingCB.EditingControlFormattedValue.ToString();
    }

二。添加DatagridviewComboBox下拉组合框内容的二种方式

//方式一
((DataGridViewComboBoxCell)this.Section_data.Rows[index1].Cells[2]).Items.Add("A" );
((DataGridViewComboBoxCell)this.Section_data.Rows[index1].Cells[2]).Items.Add("B");
((DataGridViewComboBoxCell)this.Section_data.Rows[index1].Cells[2]).Items.Add("C" );

//方式二
 List<string> ListData = new List<string> { "A", "B", "C" };
 ((DataGridViewComboBoxCell)this.Section_data.Rows[index1].Cells[2]).DataSource = ListData;

三。组合框内容的显示

//1要设置显示类型 2要设置的值为组合列表内的元素
 this.Section.ValueType = typeof(string);
 this.Section_data.Rows[index1].Cells[2].Value = "B";