vb.net - ListBoxes in Visual Basic -

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i have assignment user enter numbers list box. when user done entering numbers, compute average , standard deviation.(our professor not want use built in standard deviation functions) program have context menu , these guidelines creating menu: must create subroutine called setmenu. used enable , disable context menu based on contents of list. when list empty,clear disabled. when list has @ least 1 number in it,clear enabled. when nothing selected, delete item disabled. when selected, delete item enabled. need help, creating subroutine.

here code:

option strict on public class form1  private sub addbtn_click(byval sender system.object, byval e system.eventargs) handles addbtn.click     listbox.items.add(inputbox.text)     inputbox.text = "" end sub  private sub computebtn_click(byval sender system.object, byval e system.eventargs) handles computebtn.click     dim sum, x, number, numbersum, subtractednum integer     dim average, insideroot, squaredroot double       x = 0 listbox.items.count - 1         listbox.selectedindex = x          number = integer.parse(listbox.selecteditem.tostring)         sum = sum + number         average = sum / listbox.items.count     next     averagelbl.text = average.tostring      x = 0 listbox.items.count - 1         listbox.selectedindex = x         number = integer.parse(listbox.selecteditem.tostring)          subtractednum = cint((number - average) ^ 2)         numbersum = numbersum + subtractednum         insideroot = (numbersum / (listbox.items.count - 1))         squaredroot = insideroot ^ (1 / 2)     next     deviationlbl.text = squaredroot.tostring("n2")  end sub  private sub clearmenu_click(byval sender system.object, byval e system.eventargs) handles clearmenu.click     clearmenu.enabled = false     setmenu()     listbox.items.clear() end sub  private sub deletemenu_click(byval sender system.object, byval e system.eventargs) handles deletemenu.click     listbox.items.remove(listbox.selecteditem) end sub  private sub inputbox_textchanged(byval sender system.object, byval e system.eventargs) handles inputbox.textchanged     if isnumeric(inputbox.text) , inputbox.text <> ""         addbtn.enabled = true     else         addbtn.enabled = false     end if end sub  private sub setmenu()     'need here end sub

end class

how about:

private sub togglecontextmenuitems()      cleartoolstripmenuitem.visible = (listbox1.items.count > 0)      deletetoolstripmenuitem.visible = (listbox1.selectedindex > -1)  end sub

then call method when needed.


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