It's been such a long time since i touch vb.net and I am having a problem.. it should be a simple one but I am lost.
I want to create a loop string but before that I am trying to learn how to use the string array.
The following code is what I have but there is always error at the line g(1,0)=t
It is not an object instance. How can this be done?
Code:
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim g(,) As String
Dim t As String = "ok"
g(1, 0) = t
MsgBox(g(1, 0))
End Sub
Try this,
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim g(,) As String= {{"Hai","Hello"},{"ok","then"}}
MsgBox(g(1, 0))
End Sub
For more information refer this.
EDIT:
You can traverse your array like this
Dim g(1,1) As String
for i as integer=0 to 1
for j as integer=0 to 1
g(i,j)="Your text"
next
next
You need to give your array a size. For example:
Dim g(100, 100) As String
http://msdn.microsoft.com/en-us/library/vstudio/wak0wfyt.aspx#BKMK_CreatingAnArray
Use the REDIM statement (re-dimension) before you attempt to re-dimension (change the size) of your array.
something like
REDIM g(10, 10)
Related
I am very new to coding so please forgive me.
I have saved some example strings in an array:
Dim intArray(0 To 2) As String
intArray(0) = "I will be on time for class"
intArray(1) = "I will be prepared for class"
intArray(2) = "I will listen to the teacher and follow instructions"
lblTestSWPB.Text = intArray(0)
I know that it works when I click the button to generate for (0) - obviously.Is there a way to add something to make the label display a string at random from the array?
You may use something like: Random class
Dim rnd As New Random 'Make sure that you declare it as New,
'otherwise, it thorws an Exception(NullReferenceException)
Dim intArray(0 To 2) As String
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
intArray(0) = "I will be on time for class"
intArray(1) = "I will be prepared for class"
intArray(2) = "I will listen to the teacher and follow instructions"
End Sub
Private Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
lblTestSWPB.Text = intArray(rnd.Next(0, 3))
End Sub
Note that rnd.Next is a Function that returns a random Integer from the minimum is the inclusive lower bound and the maximum is the exclusive upper bound.(Thanks to #Enigmativity for the correction.) Click this link if this answer is still unclear for you
I am basically trying to create an array to export checked items onto a word document. But I am getting an error saying
"Object reference not set to an instance of object."
and
"Referenced 'SelectedMutualFunds' has a value of 'Nothing'
Below is my code:
Public Class ExportFunds
Public SelectedMutualFunds() As String
Private Sub ExportFundOkButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ExportFundOkButton.Click
Dim i As Integer
Dim array_Counter As Integer
array_Counter = 0
For i = 0 To ExportFundCheckedListBox.Items.Count() - 1
If ExportFundCheckedListBox.GetItemCheckState(i) = CheckState.Checked Then
SelectedMutualFunds(array_Counter) = ExportFundCheckedListBox.Items(i).ToString
array_Counter += 1
End If
Next
Me.Close()
End Sub
Can someone please help me solve this issue?
You need to provide length to your string array
Public SelectedMutualFunds() As String
to the following within ExportFundOkButton_Click before you use, preferably just before the for loop.
Redim SelectedMutualFunds(ExportFundCheckedListBox.Items.Count() - 1)
You can get this down to a one-liner and fix the NullReference exception at the same time:
Private Sub ExportFundOkButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ExportFundOkButton.Click
SelectedMutualFunds = ExportFundCheckedListBox.Items.Where(Function(i) i.CheckState = CheckState.Checked).Select(Function(i) i.ToString()).ToArray()
Me.Close()
End Sub
Or, slightly longer but easier to read:
Private Sub ExportFundOkButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ExportFundOkButton.Click
SelectedMutualFunds = ExportFundCheckedListBox.Items.
Where(Function(i) i.CheckState = CheckState.Checked).
Select(Function(i) i.ToString()).
ToArray()
Me.Close()
End Sub
So I am trying to use a listbox to access variables in my 2D array. I am unsure what is the best way to do this. Right now I am using the selectedindex of the listbox to access it but I am only seeing the second dimension being show in my message box. Any help would be appreciated.
Option Explicit On
Option Strict On
Option Infer Off
Public Class Form1
Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
lstInventory.Items.Add("Hand Grenade")
lstInventory.Items.Add("9mm Ammo Box")
lstInventory.Items.Add(".40 Ammo Box")
lstInventory.SelectedIndex = 0
End Sub
Dim dblInventoryItem(,) As Double = {{10.99, 5},
{5.99, 10},
{8.99, 8}}
Private Sub btnCheck_Click(sender As System.Object, e As System.EventArgs) Handles btnCheck.Click
Dim intRow As Integer = lstInventory.SelectedIndex
MessageBox.Show(dblInventoryItem(intRow, 1).ToString)
End Sub
End Class
You don't want to use a multi-dimensional array here.
The OOP way to do this would be to define inventory item as its own class or structure, and use instances to both populate your list box and store the inventory item price and quantity.
Something like:
Public Class Form1
Structure InventoryItem
Public Sub New(ByVal itmName As String, ByVal itmPrice As Double, ByVal itmQty As Integer)
Name = itmName : Price = itmName : Quantity = itmQty
End Sub
Dim Name As String
Dim Price As Double
Dim Quantity As Integer
End Structure
Dim invItems As New List(Of InventoryItem)
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
invItems.Add(New InventoryItem("Hand Grenade", 10.99, 5))
'' ... Add your additional items here
For Each i As InventoryItem In invItems
lstInventory.Items.Add(i.Name)
Next
End Sub
Private Sub btnCheck_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCheck.Click
Dim invItem As InventoryItem = invItems(lstInventoryItems.SelectedIndex)
MessageBox.Show(invItem.Name & "," & invItem.Price & "," & invItem.Quantity)
End Sub
End Class
I wrote the following code:
Public Class Form1
Private Structure udtThing
Dim SomeText As String
Dim SomeElements() As String
Public Shared Function CreateInstance() As udtThing
Dim result As New udtThing
result.SomeText = String.Empty
ReDim result.SomeElements(2)
result.SomeElements(0) = String.Empty
result.SomeElements(1) = String.Empty
result.SomeElements(2) = String.Empty
Return result
End Function
End Structure
Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim nThings() As udtThing
nThings = Array.CreateInstance(GetType(udtThing), 10)
End Sub
End Class
I partly works, nThings becomes an array of 11 udtThings.
But .SomeElements is not redimmed to 3 strings of String.Empty, but it is "Nothing" instead.
Does anybody see where I went wrong?
Thank you very much!
By design, a Redim is required. Array.CreateInstance() isn't going to perform that operation, it can't guess what size is required. You'll have to help:
Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim nThings(10) As udtThing
For ix As Integer = 0 To UBound(nThings)
nThings(ix) = udtThing.CreateInstance()
Next
End Sub
I have a filepath that I would like to pull the starting directory job number from the beginning of the filepath. Except I don't know how to just pull the number string out of the filepath string. (i.e.: filepath= Q:\2456_blah_blah\file.txt - or something) I'd like to just pull '2456' as a string,
then put that number string into TextBox2 I've created on my form.
The code I have so far spits out a '0' instead of the number string desired.
Any help would be much appreciated.
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Me.OpenFileDialog1.FileName = Nothing
If Me.OpenFileDialog1.ShowDialog = System.Windows.Forms.DialogResult.OK Then
Me.TextBox1.Text = Me.OpenFileDialog1.FileName
End If
If GetInfo() = True Then
For Each Xitem In ExcelRowList
Dim lvitem As ListViewItem
lvitem = Me.ListView1.Items.Add(Xitem.C1)
Next
End If
'''Here is where I call the GetFilePathOnly function
TextBox2.Text = GetFilePathOnly(TextBox1.Text)
End Sub
Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
End Sub
'''Section below is what defines my number string, then I call it above for the Button1.Click operation(towards the end)
Private Function GetFilePathOnly(ByVal Fullpath As String) As String
Dim File As String = Fullpath
Dim number As Double = Val(File)
Dim outcome As String = number.ToString 'File.Substring(0, File.LastIndexOf("\") + 1)
Return outcome
End Function
Thanks
You could also use a regular expression easily.
Dim numRegex As New Regex("\d+")
Dim number As String = numRegex.Match("Q:\2456_blah_blah\file.txt").Value
A lazy way would be to use Split:
TextBox2.Text = path.Split("\")(1).Split("_")(0)