vb.net 在运行时以编程方式将值添加到下拉列表
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Add values to dropdown list programatically at run time
提问by ubaid ashraf
I am trying to change the list item values of a dropdown list based on values of an other dropdown list. The list values of drpAdult range from 0-9 and list values of drpInfant range from 0-(Value of drpAdult selected).
我正在尝试根据其他下拉列表的值更改下拉列表的列表项值。drpAdult 的列表值范围为 0-9，drpInfant 的列表值范围为 0-（选择了 drpAdult 的值）。
So, for example, if I select 5 in the drpAdult dropdown, the range of list item values of drpInfant will be from 0-5.
因此，例如，如果我在 drpAdult 下拉列表中选择 5，则 drpInfant 的列表项值范围将是 0-5。
I have written the code below, but it is not populating the values in the drpInfant dropdown, which I am trying to insert on drpAdult_SelectedIndexChanged event.
我已经编写了下面的代码，但它没有填充 drpInfant 下拉列表中的值，我试图在 drpAdult_SelectedIndexChanged 事件上插入该值。
Protected Sub drpAdult_SelectedIndexChanged(ByVal sender As Object,
ByVal e As EventArgs) Handles drpAdult.SelectedIndexChanged
Dim count As Integer
count = drpAdult.Items.Count
Dim i As Integer
i = 0
While count > 0
i = i + 1
drpInfant.Items.Add(New ListItem(i, i))
count = count - 1
End While
End Sub
What might cause this problem, and how can I resolve it?
什么可能导致此问题，我该如何解决？
采纳答案by Tim Schmelter
Not sure what "is not working"means, but this seems to be easier anyway:
不确定“不起作用”是什么意思，但这似乎更容易：
Dim newCount = drpAdult.Items.Count + 1
For i As Int32 = 0 To newCount
Dim newItem As New ListItem(i.ToString, i.ToString)
drpInfant.Items.Add(newItem)
Next
回答by Patrick Allwood
Something along these lines...
沿着这些路线的东西......
drpInfant.Items.Clear()
dim n as Integer
Integer.TryParse(drpAdult.SelectedValue, n)
For i as integer = 1 to n
if n < i Then Exit For 'it's not fun when this condition happens in VB
drpInfant.Items.Add(New ListItem(i, i))
Next
回答by Santosh Panda
You can try this. I have tested this & working fine:
你可以试试这个。我已经测试过这个并且工作正常：
Protected Sub drpAdult_SelectedIndexChanged(sender As Object, e As EventArgs)
drpInfant.Items.Clear()
Dim count As Integer = drpAdult.SelectedIndex
Dim i As Integer = 0
While count >= 0
drpInfant.Items.Add(New ListItem(i.ToString(), i.ToString()))
i = i + 1
count = count - 1
End While
End Sub
