Question

关于vb listbox

求高手解释
If List1.ListIndex >= 0 Then
n = InStr(List1.Text, " ")
l = Len(List1.Text)
n = n + 1
Label11.Caption = Val(Label11.Caption) - Val(Mid(List1.Text, n, l - n))

Answer 1

If List1.ListIndex >= 0 Then'记录不空
n = InStr(List1.Text, " ")'找出有空格的位置
l = Len(List1.Text)'长度
n = n + 1'空格下位置
Label11.Caption = Val(Label11.Caption) - Val(Mid(List1.Text, n, l - n))'用标签里的数字减去List1.Text中空格后取出的数据,然后送标签显示

Answer 2

Private Sub List1_DblClick()
Dim i As Long
Dim s As String

If List1.ListIndex > -1 Then
s = List1.List(List1.ListIndex)
If List2.ListCount > 0 Then
For i = 0 To List2.ListCount - 1
If s = List2.List(i) Then
MsgBox "已经选过了。", vbOKCancel, "提示"
Exit For
End If
Next i
If i = List2.ListCount Then List2.AddItem s
Else
List2.AddItem s
End If
End If
End Sub

Private Sub Form_Load()
Dim i As Long
For i = 1 To 5
List1.AddItem "菜单" & i
Next i
End Sub