managing multi-listboxes

There have been several folks struggling with how to manage a dual listbox style application where items from a master list are moved to a destination list. I wrote some code to do that many years ago. This is an updated version with comments. I am hoping folks can follow along. When running the program looks like this:

[[image:multi-listbox.jpg]]

----

Here is the code:

[[code format="qbasic"]]
'Friuty List - an example of how to manage a listbox as a destination list building
'  the list from a master listbox.  This would work with comboboxes also.
'by Brad Moore - placed into the Public Domain Jan 2006

nomainwin

'this is how many entries the destination list box can hold
maxEntries = 100

'create the arrays
dim arrayOne$(12)
dim arrayTwo$(maxEntries)

'this is the master data - you can do this with read/data statements also,
'  wondering how this works? - check out the WORD$ function in the helpfile.
a$ = "Apples Bananas Cherries Figs Grapefriut Honeydew Kiwi Lime Mango Nectarine Papaya Pear"
for x = 1 to 12 : arrayOne$(x) = word$(a$,x) : next x

'initialize our counter for items in the destination listbox
idx = 0

'setup the window and controls
WindowWidth = 280
WindowHeight = 260
UpperLeftX = int((DisplayWidth/2)-(WindowWidth/2))
UpperLeftY = int((DisplayHeight/2)-(WindowHeight/2))

listbox #main.lbx1,arrayOne$(),wait,10,10,100,170
listbox #main.lbx2,arrayTwo$(),wait,158,10,100,170
button #main.moveBtn,">",[move],UL,114,30,40,30
button #main.deleteBtn,"Delete",[delete],UL,114,62,40,30
button #main.deleteBtn,"Sort",[sort],UL,114,94,40,30
button #main.closeBtn, "Close",[quit],UL,158,189,100,30
button #main.inspectBtn, "Inspect Array",[inspect],UL,52,189,100,30

'open the window
open "Friuty List" for dialog as #main
print #main,"trapclose [quit]"
print #main.lbx1,"selectindex 1"
wait

[move]
'get the index value for the item in the master list
print #main.lbx1,"selectionindex? i"
'make sure there is room to add another item
if idx = maxEntries then
    notice "The destination list already contains the maximum number of entries"
    wait
end if
'increment the index and add the item
idx = idx + 1
arrayTwo$(idx) = arrayOne$(i)
'reload causes the listbox view to be refreshed so our item shows up
print #main.lbx2,"reload"
wait

[delete]
'get the index value for the item in the destination list
print #main.lbx2,"selectionindex? i"
'if this is not the last item we need to shift the array up to fill the gap
if i < idx then
   for x = i to idx - 1
      arrayTwo$(x) = arrayTwo$(x+1)
   next x
end if
'set the last item to a null string
arrayTwo$(idx) = ""
'decrement the total number of items in the destination array
idx = idx - 1
'reload causes the listbox view to be refreshed so our item shows up
print #main.lbx2,"reload"
wait


[inspect]
'inspect opens a new window in dialog modal form - set up that window
WindowWidth = 372
WindowHeight = 470
UpperLeftX = INT((DisplayWidth-(2 * WindowWidth))/2)
UpperLeftY = INT((DisplayHeight-(2 * WindowHeight))/2)
button  #inspect.closeBtn, "Close", [closeMe], UL, 225, 395, 125, 30
texteditor  #inspect.tedit, 9, 13, 340, 375
'open the window
Open "Array Inspector" for Dialog_modal as #inspect
#inspect "trapclose [closeMe]"
#inspect "font ms_sans_serif 10"

'initialize the output string
if idx = 0 then
    out$ = "There are no items in the destination array."
else
    out$ = "There are " + str$(idx) + " items in the destination array." + chr$(10)
end if

'add the array items to the output string.  Note the right$ trick which pads index with leading zeros
for x = 1 to idx
    out$ = out$ + "Item " + right$("000" + str$(x),3) + " = " + arrayTwo$(x) + chr$(10)
next x
'dump the output string to the texteditor
#inspect.tedit out$
Wait

[closeMe]
close #inspect
wait


[sort]
'if there is more than one item in the destination array call the sort function to sort it
if idx > 1 then sort arrayTwo$(), 1, idx
'reload causes the listbox view to be refreshed so our item shows up
print #main.lbx2,"reload"
wait

[quit]
close #main
end
[[code]]

[[user:bradmoore]]