I'm trying to make a simple login program, but I'm having troubles with assigning a value to my two arrays "User()" and "Pass()". I have the following code on a form titled "frmCreate". This is the form I will be using to create the accounts.
Public Class frmCreate
Dim passs() As String
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles btnCreate.Click
If Not (txtUser.Text = "") And Not (txtPass.Text = "") Then
userCount = userCount + 1
User(userCount) = txtUser.Text
Pass(userCount) = txtPass.Text
Else
MsgBox("Please enter a username or password")
End If
End Sub
Private Sub Button1_Click_1(sender As Object, e As EventArgs) Handles Button1.Click
passs(0) = "hi"
End Sub
End Class
The issue I'm getting is as follows:
Error in array
The txtPass and txtUser are both text boxes, which can be edited by the user.
Any help would be much appreciated! (Also, I tried mucking around with the variables and all, the strings after the = sign aren't the problem, and when I set the "userCount" inside the brackets to "0" for example, it still returned the same error)
EDIT Added code as text, rather then image (image still there). Note the extra few lines at the end where I set a new array which I named passs() to "hi". The dim is also further up. If I am declaring my variables incorrectly, please let me know.
EDIT2 Ok, I changed my declaration of "User()" and "Pass()" to = {}. Now my problem is that I'm getting the error that the value is out of the bounds of the array. I understand that this happens when you try to call on a non existent value which is outside the arrays boundaries, but the array I set has no boundaries, and I'm just trying to give it a value, not call on one.
EDIT3 Ugh... Ok tweaked a bit, I've found that if I add an unused value to "User()" then it is able to replace it. So I can get the program to replace already existent values in arrays, but I can not get it to create new values in arrays.
It would appear your User variable is NULL. I presume this is intended to be a list of strings or something similar?
You should check the place you are initializing this variable to make sure it is being created...
You could add an
If User Is Nothing
line at the start of the function to check this, and if the list is null at this point create it.
I have discovered what it is I was doing wrong. See, I thought when I declared a variable with empty parenthesis, it created a dynamic variable. This is obviously not the case. Since setting the size of my variable to the ludicrous size of 50,000, my program now works. Thanks to all who tried to help, and sorry for asking the wrong thing :/
Your problem here is that you only defined the variable array. You never reserved a spot for the array values in memory. Therefore your variable has a value of Nothing.
Before assigning the first item, you must assign room for it...
'We say we want an array
Dim passs() As String
'We ask the memory to reserve six spots for our array
passs = New String(5) {}
'We assign the first spot to the String "hi"
passs(0) = "hi"
However, if you don't know how many items you are going to add in your array, I strongly suggest you to use a List(of T) instead :
Dim passs As New List(of String)
passs.Add("hi")
Related
I have been working on a project, and am attempting to make a new array for data. I have tried making an empty array with Dim Name() As String = {}. I am using a ListView, and the way I have done it there are blank spots where I have gotten rid of data. This is my current code:
Sub English(ByVal Country() As String, ByVal Language() As String)
rbDisplayallData.Checked = False
lstResults.Visible = True
lstResults.Items.Clear()
lstResults.Columns.Clear()
With lstResults
.View = View.Details
.Columns.Add("English Speaking Countries", 200, HorizontalAlignment.Left)
End With
For i = 0 To 181
Dim EnglishSpeakingCountries(i) As String
If Language(i) = "English" Then
EnglishSpeakingCountries(i) = Country(i)
End If
lstResults.Items.Add(New ListViewItem({EnglishSpeakingCountries(i)}))
Next
End Sub
I am trying to get rid of these spaces.
I Was thinking if I were to compact the array or make a new one with the same data going into a new array it would fix the issue.
If you have a solution please let me know.
There are two things that could be considered an empty array
An array with no elements, i.e. a Length of zero.
An array where every element is Nothing.
All arrays are fixed-length. Once you create an array with a particular number of elements, it always has that number of elements. You can use ReDim Preserve or Array.Resize but, in both those cases, what actually happens is that a new array is created and the elements copied from the old array. The new array is assigned to the same variable but anywhere the old array is referenced, it will still have that same number of elements. Try running this code to see that in action:
Dim a1 As String() = {}
Dim a2 As String() = {"First", "Second", "Third"}
Dim b1 = a1
Dim b2 = a2
Console.WriteLine(a1.Length)
Console.WriteLine(a2.Length)
Console.WriteLine(b1.Length)
Console.WriteLine(b2.Length)
Console.WriteLine()
ReDim Preserve a1(2)
Array.Resize(a2, 6)
Console.WriteLine(a1.Length)
Console.WriteLine(a2.Length)
Console.WriteLine(b1.Length)
Console.WriteLine(b2.Length)
Console.ReadLine()
Output:
0
3
0
3
3
6
0
3
As you'll be able to see, a1 and a2 end up referring to new arrays with the specified lengths but the original arrays with the original lengths still exist and are still accessible via b1 and b2.
If you start with an array with no elements then you can use ReDim Preserve or Array.Resize to give the appearance of resizing the array but that's not really what's happening and that should generally be avoided. If you know how many elements you'll end up with then you could create an array of that size and then set each element in turn. You'd need to keep track of the next element index though, so that's still a bit tedious.
Generally speaking, if you want an array-like data structure but you want it to be able to grow and shrink as required, you should use a collection. The most common collection is the List(Of T), where T is any type you care to specify in your code. If you want to store String objects then use a List(Of String). You can call Add to append a new item to the end of the list, as well as Insert, Remove and RemoveAt methods. You can also get or set an item by index, just as you can do for array elements.
Note that a List(Of T) actually uses an array internally and uses the aforementioned method of "resizing" that array. It optimises the process somewhat though, which makes the code easier for you to write and large collections more efficient to use.
It's worth noting that, in your own code, the Columns and Items properties of your ListView are both collections, although they are slightly different to the List(Of T) class.
Looking at your original code, this:
For i = 0 To 181
Dim EnglishSpeakingCountries(i) As String
If Language(i) = "English" Then
EnglishSpeakingCountries(i) = Country(i)
End If
lstResults.Items.Add(New ListViewItem({EnglishSpeakingCountries(i)}))
Next
could be changed to this:
Dim englishSpeakingCountries As New List(Of String)
For i = 0 To 181
If Language(i) = "English" Then
englishSpeakingCountries.Add(Country(i))
lstResults.Items.Add(Countries(i))
End If
Next
Note that you're just adding items to two collections. I guess the question is whether you actually need this extra collection at all. If you do want to use it later then you need to assign it to a member variable rather than a local variable. If you don't need it later then don't create it at all. As I said, you're already adding items to a collection in the ListView. Maybe that's all you need, but you haven't provided enough info for us to know.
I have file with tags and targets, this is example:
TAG1|TARGET1,TARGET2
TAG2|TARGET3,TARGET4
I start by creating String Array using File.ReadAllLines
Dim MAIN As String() = File.ReadAllLines("")
At some point I have one of targets and I need to know what was the tag index (which array line is it), so for example if I have TARGET3 I want to know it's in second line so it's in MAIN(1) and then I can grab TAG = TAG2.
I can't get it working, I tried few methods:
Array.IndexOf(MAIN,"TARGET3")
always returned -1, it worked with full string tho,
Array.IndexOf(MAIN,"TAG2|TARGET3,TARGET4")
returned 1. I tried with Array.FindIndex, was the same.
So my question is: how to get index of partial array item. Thank you for any help.
You can use Linq to search your array in this way
Dim search = "TARGET3"
Dim line = MAIN.FirstOrDefault(Function(x) x.Contains(search))
This will return directly the line with the matching word
I have a text-file(customers.txt) from which I'm trying to extract certain pieces of data from to place in a list-box(lstReportsUnresolved). I'm using commas to split up lines in the text-box and at a certain split, if the text is equal to "No" then the previous split is added to the listbox.
Code:
Private Sub btnUnresolved_Click(sender As Object, e As EventArgs) Handles btnUnresolved.Click
For Each line As String In File.ReadLines("customers.txt")
Dim data As String() = line.Split(",")
If data(18) = "No" Then
lstReportsUnresolved.Items.Add(data(17))
End If
If data(20) = "No" Then
lstReportsUnresolved.Items.Add(data(19))
End If
If data(22) = "No" Then
lstReportsUnresolved.Items.Add(data(21))
End If
If data(24) = "No" Then
lstReportsUnresolved.Items.Add(data(23))
End If
Next
End Sub
It was working fine earlier, but I came back and now try to run it and it stops and highlights the line If data(18)="No" Thenwith the error "An unhandled exception of type 'System.IndexOutOfRangeException' occurred in Semester Two Project.exe" with additional info saying "Index was outside the bounds of the array."
Here is an example of a line from the text file
Mark,Barry,07/04/1996,Redbrook,Sandymount,Dublin,Ireland,094-378231,085-0983623,markbarry96#gmail.com,Basic Cable,VB Fibre Broadband,VB Sports,VB Movies,Chat Chat Phone,VB Anywhere,VB Data,Unavailable Services,Yes,Incorrect Bill,Yes,Poor Tv Reception,No, ,No
Thank you for your help and time
It could be due to File.ReadLines(). The method only reads some (or maybe even one) lines at a time, meaning it could have read less (if it's split into lines) than required to make your split return an array of at least 19 elements. You should use File.ReadAllLines() instead.
Just replace File.ReadLines() with File.ReadAllLines():
For Each line As String In File.ReadAllLines("customers.txt")
If this is a big file and you don't want to use File.ReadAllLines(), you could instead check the end of the array (if the "No" always appears there), instead of having a static index.
EDIT:
Actually, either if you use ReadLines or ReadAllLines you should probably stick with checking from the end:
If data(data.Length - 1) = "No" Then
lstReportsUnresolved.Items.Add(data(data.Length - 2))
End If
For certain, technical, reasons, we cannot use styles in word. In an effort to speed up applying global properties over and over, I've created a class that can read from a simple xml style-sheet. The sheet contains different "paragraphs." Each paragraph simply stores the paragraph properties that we use the most.
I'm used to C++ where I can use dynamic memory and I'm trying to replicate the behavior of a dynamically allocated array. However, when I attempt to re-dim I get the error message "Array arleady dimensioned."
My research on the MSDN suggests that in order to ReDim the array has to be Global or in the "general declaration context" This makes me think it might simply not be possible to do it in a class.
Excerpt from MSDN:
"You can use ReDim only at procedure level. Therefore, the declaration
context for the variable must be a procedure; it can't be a source
file, a namespace, an interface, a class, a structure, a module, or a
block."
I have attempted to search stack overflow for "Word VBA Array already dimensioned" and went through all 3 pages of results with no avail.
private type pStyle 'Definition removed because it's not needed
private Paragraphs(0) As pStyle 'Initially an empty array of paragraphs
later I have the following function
Public Function AddEmpty()
'Create space
count = count + 1
ReDim Preserve Paragraphs(count)
AddEmpty = count
End Function
Please let me know if any ideas. I would prefer to not have to "estimate" the number of paragraph styles we will need for each style sheet as every file is different.
Private Paragraphs(0) As ...
This is not an empty array, rather it is a fixed length array with 1 element.
For a dynamic array - one you will later redimension - just declare it as:
Private Paragraphs() As ...
Dim numbers(10) As Integer
MsgBox (UBound(numbers))
ReDim numbers(4)
MsgBox (UBound(numbers))
Above code will throw array-already-dimensioned. we can do like
ReDim numbers(10) As Integer
MsgBox (UBound(numbers))
ReDim numbers(4)
MsgBox (UBound(numbers))
I have a short app that check if my music files are names to a specific routine (track number and then track name), but I'm getting an error whenever there are no files that need renaming, because the array in initialised, but the first item is nothing, null, empty (however VB refers to it).
To try and fix this, I'm running this check, but I'm still getting an error.
' Array declared like this
Dim nc_full_names(0) As String
<Code goes here to ReDim 'nc_full_names' and add the file name to the array, if a file needs renaming>
For i = 0 To UBound(nc_full_names)
'Checking if the array element actually has something in it like this
If Not nc_full_names Is Nothing Then
My.Computer.FileSystem.RenameFile(nc_full_names(i), nc_new_names(i))
Else
Exit For
End If
Next i
Here is the error that I am getting -
Argument cannont be nothing. Parameter name: file
Can anyone tell me the correct way to carry out this check?
I found that the answer was to check the first element in the array, as opposed the array itself. Thus, changing this...
If Not nc_full_names Is Nothing Then
...to this...
If Not nc_full_names(i) Is Nothing Then
...works just fine.
You can also start with a truly empty array:
Dim nc_full_names(-1) As String
Now nc_full_names.Length = 0.