从一个drpdown复制到另一个 [英] copy from one drpdown to another one by one

问题描述

我有两个下拉菜单dr1，dr2和一个按钮. dr1包含项目.我希望当我从dr1中选择一个项目并单击按钮时，必须将选定的项目复制到dr2中.当我从dr1中选择item2并再次按下按钮时，它将将该项目复制到dr2中.我已经使用了代码，但我无法正常工作并给出错误.有人可以告诉我我该怎么做.

i have two dropdowns dr1,dr2 and a button. dr1 contains items. i want that when i select an item from dr1 and click on button so that selected item must be coppied into dr2. when i select item2 from dr1 and press the button again it copies that item into dr2. i have used a code but i doesnt work and gives and error. can somebody tell me what i need to do.

protected void Button1_Click(object sender, EventArgs e)
    {
        DropDownList2.Items.Add(DropDownList1.SelectedItem);

    }

推荐答案

您可以在CP上查看该文章；

ASP.NET中的多选下拉列表 [

You can look at that article on CP;

Multi select Dropdown list in ASP.NET[^]

This will help you select multiple items from a drop down. If you do not want to use this, instead you can use a listbox.
Good luck.

尝试一下:

Try this:

DropDownList2.Items.Add(DropDownList1.Items[DropDownList1.SelectedIndex]);

您*可能*需要先这样做:

You *might* need to do this first:

DropDownList2.SelectedIndex = -1;

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