vb011 list boxes vb15. vb012 list boxes a list box contains a list of items one underneath the other...
TRANSCRIPT
![Page 1: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/1.jpg)
VB01 1
List Boxes
VB15
![Page 2: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/2.jpg)
VB01 2
List Boxes
• A list box contains a list of items one underneath the other
DanPeterJaneRobertElaineNiamhAlan
![Page 3: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/3.jpg)
VB01 3
lstName.AddItem
lstNaughty.AddItem “Peter”
Adds Peter to the list called lstNaughty
Peter
![Page 4: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/4.jpg)
VB01 4
lstName.AddItem
lstNaughty.AddItem “Mike”
Adds Mike to the list called lstNaughty
PeterMike
![Page 5: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/5.jpg)
VB01 5
lstName.Clear
lstNaughty.Clear
Removes all the items from the list box
![Page 6: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/6.jpg)
VB01 6
lstName.List (int)
RodJaneFreedyZippyBungleJeferyArcher
Individual list box items can be referenced by a subscript just like an array
lstNaughty.List (0) is “Rod”
lstNaughty.List (3) is “Zippy”
lstNaughty.List (4) is “Bungle”
![Page 7: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/7.jpg)
VB01 7
lstName.List (int)
RodJaneFreedyZippyBungleJeferyArcher
The .list method can also be used to change an item.
lstNaughty.List (3) = “Peter”
RodJaneFreedyPeterBungleJeferyArcher
![Page 8: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/8.jpg)
VB01 8
lstName.ListCount
• The .ListCount method is used to determine the number of items in the list
• lntNaughty.ListCount is 7
RodJaneFreedyPeterBungleJeferyArcher
![Page 9: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/9.jpg)
VB01 9
lstName.RemoveItem (int)
• The .RemoveItem method is used to remove a particular item
• lntNaughty.RemoveItem (4)
RodJaneFreedyPeterBungleJeferyArcher
RodJaneFreedyPeterJeferyArcher
![Page 10: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/10.jpg)
VB01 10
Using List Boxes- Example 1
RodJaneFreedyZippy
PatRory
Add name
Naughty
Nice
Naughty NiceSanta’s List
![Page 11: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/11.jpg)
VB01 11
Santa’s List
RodJaneFreedyZippy
PatRory
Add name
Naughty
Nice
Naughty Nice
lstNaughty lstNice
optNaughty
txtName
![Page 12: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/12.jpg)
VB01 12
Santa’s List - Code
strName = txtName.Text
If optNaughty.value then
lstNaughty.AddItem strName
Else
lstNice.AddItem strName
End If
![Page 13: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/13.jpg)
VB01 13
Using List Boxes- Example 2
• lstNaughty is a list of names• Write a VB program that
counts the number names in the list that begin with the letter R and puts this number into a variable called intTotalCount
RodJaneRyuichiRoryBungleJeferyArcher
![Page 14: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/14.jpg)
VB01 14
Algorithm
Set intTotalCount = 0
For each name
If it begins with “R” then
Add one to intTotalCount
Next name
![Page 15: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/15.jpg)
VB01 15
Dim intTotalCount As IntegerDim strName as StringintTotalCount = 0For n = 0 to lstNaughty.ListCount - 1
strName = lstNaughty.List (n)If left (strName, 1) = “R” Then
intTotalCount = intTotalCount + 1End If
Next n
![Page 16: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/16.jpg)
VB01 16
Dim intTotalCount As IntegerDim strName as StringintTotalCount = 0For n = 0 to lstNaughty.ListCount - 1
strName = lstNaughty.List (n)If left (strName, 1) = “R” Then
intTotalCount = intTotalCount + 1End If
Next n
![Page 17: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/17.jpg)
VB01 17
Dim intTotalCount As IntegerDim strName as StringintTotalCount = 0For n = 0 to lstNaughty.ListCount - 1
strName = lstNaughty.List (n)If left (strName, 1) = “R” Then
intTotalCount = intTotalCount + 1End If
Next n
![Page 18: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/18.jpg)
VB01 18
Dim intTotalCount As IntegerDim strName as StringintTotalCount = 0For n = 0 to lstNaughty.ListCount - 1
strName = lstNaughty.List (n)If left (strName, 1) = “R” OR left (strName, 1) = “r” Then
intTotalCount = intTotalCount + 1End If
Next n
![Page 19: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/19.jpg)
VB01 19
Using List Boxes - Example 3
RodJaneRyuichiRoryBungleJeferyArcher
9874596
Two list boxes lstNames and lstAges are used to store the names and ages of children respectively.
The nth item in lstAges is the age of the child whose name in the nth item in lstNames
Write a program that finds the name of the youngest child and stores it in strYoungest
![Page 20: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/20.jpg)
VB01 20
Algorithm• Set strYoungest to the first name in lstNames• Set the intYoungestSoFar to the first age in
lstAges• Go though the ages one by one• For each item in intAges• If it is smaller than intYoungestSoFar then
– Set intYoungerstSoFar to it– Set strYoungest to the corresponding name
• Go on to the next one
![Page 21: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/21.jpg)
VB01 21
Dim strYoungest As StringDim intYoungestSoFar As IntegerstrYoungest = lstNames.List(0)intYoungestSoFar = lstAges.List(0)For n = 0 to lstAges.ListCount - 1
If lstAges.List(n) < intYoungestSoFar ThenintYoungestSoFar = lstAges.List(n)strYoungest = lstNames.List(n)
End IfNext n
![Page 22: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/22.jpg)
VB01 22
Dim strYoungest As StringDim intYoungestSoFar As IntegerstrYoungest = lstNames.List(0)intYoungestSoFar = lstAges.List(0)For n = 0 to lstAges.ListCount - 1
If lstAges.List(n) < intYoungestSoFar ThenintYoungestSoFar = lstAges.List(n)strYoungest = lstNames.List(n)
End IfNext n
![Page 23: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/23.jpg)
VB01 23
Dim strYoungest As StringDim intYoungestSoFar As IntegerstrYoungest = lstNames.List(0)intYoungestSoFar = lstAges.List(0)For n = 0 to lstAges.ListCount - 1
If lstAges.List(n) < intYoungestSoFar ThenintYoungestSoFar = lstAges.List(n)strYoungest = lstNames.List(n)
End IfNext n
![Page 24: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/24.jpg)
VB01 24
Dim strYoungest As StringDim intYoungestSoFar As IntegerstrYoungest = lstNames.List(0)intYoungestSoFar = lstAges.List(0)For n = 0 to lstAges.ListCount - 1
If lstAges.List(n) < intYoungestSoFar ThenintYoungestSoFar = lstAges.List(n)strYoungest = lstNames.List(n)
End IfNext n
![Page 25: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/25.jpg)
VB01 25
Dim strYoungest As StringDim intYoungestSoFar As IntegerstrYoungest = lstNames.List(0)intYoungestSoFar = lstAges.List(0)For n = 1 to lstAges.ListCount - 1
If lstAges.List(n) < intYoungestSoFar ThenintYoungestSoFar = lstAges.List(n)strYoungest = lstNames.List(n)
End IfNext n
![Page 26: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/26.jpg)
VB01 26
Using List Boxes - Example 3
RodJaneRyuichiRoryBungleJeferyArcher
910
71415
96
Two list boxes lstNames and lstAges are used to store the names and ages of children respectively.
The nth iten in lstAges is the age of the child whose name in the nth item in lstNames
Write a program that removes all of the children who are 10 years of age or older
![Page 27: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/27.jpg)
VB01 27
RodJaneRyuichiRoryBungleJeferyArcher
910
71415
96
RodRyuichiJeferyArcher
9796
![Page 28: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/28.jpg)
VB01 28
Algorithm
For each child
If age >= 10 then
Delete that childs name from the list
End If
Next child
![Page 29: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/29.jpg)
VB01 29
For n = 0 to lstAges.ListCount - 1
If lstAges.List (n) >= 10 Then
lstNames.RemoveItem (n)
End If
Next n
![Page 30: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/30.jpg)
VB01 30
RodJaneRyuichiRoryBungleJeferyArcher
910
71415
96
RodRyuichiRoryJefery
910
71415
96
What happened!!???
![Page 31: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/31.jpg)
VB01 31
RodJaneRyuichiRoryBungleJeferyArcher
910
71415
96
RodRyuichiRoryJefery
910
71415
96
What happened!!???
The ages weren’t removed
Wrong names removed
![Page 32: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/32.jpg)
VB01 32
For n = 0 to lstAges.ListCount - 1
If lstAges.List (n) >= 10 Then
lstNames.RemoveItem (n)
lstAges.RemoveItem (n)
End If
Next n This will remove ages
![Page 33: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/33.jpg)
VB01 33
For n = 0 to lstAges.ListCount - 1
If lstAges.List (n) >= 10 Then
lstNames.RemoveItem (n)
lstAges.RemoveItem (n)
As items are deleted the size of the list box changes.
Does n count to whatever ListCount-1 was at the start or does it check ListCount every time? ?
![Page 34: VB011 List Boxes VB15. VB012 List Boxes A list box contains a list of items one underneath the other Dan Peter Jane Robert Elaine Niamh Alan](https://reader036.vdocument.in/reader036/viewer/2022062301/56649f275503460f94c3fe9b/html5/thumbnails/34.jpg)
VB01 34
n = 0
Do Until n > lstAge.ListCount
If lstAges.List (n) >= 10 then
lstAges.RemoveItem (n)
lstNames.RemoveItem (n)
Else
n = n + 1
End If
Loop