How do I create an array of PictureBox using a loop?

Question

I need to create 49 PictureBoxes and then place them on a Form. I was thinking in something like

Public Class Form1
   Dim grid() as PictureBox
   Public Sub Form_Load () Handles Me.Load
      For i = 0 to 48
         grid(i) = New PictureBox
         grid(i).Visible = True
         Me.Controls.Add(grid(i))
      Next
   End Sub

Debug console tells me grid(i) = Nothing

I know, but if I manage to create them, spreading them out would be easy — RicRev
– RicRev, Commented Oct 31, 2017 at 0:34

score 2 · Accepted Answer · 2017-10-31 00:50:20Z

2

Dim grid(0 to 48) As PictureBox
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
        For i = 0 To 48
            grid(i) = New PictureBox
            Me.Controls.Add(grid(i))
        Next
    End Sub

or

 Dim grid(48) As PictureBox
        Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
            For i = 0 To 48
                grid(i) = New PictureBox
                Me.Controls.Add(grid(i))
            Next
        End Sub

or

Dim grid() As PictureBox
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
        redim grid(48)
        For i = 0 To 48
            grid(i) = New PictureBox
            Me.Controls.Add(grid(i))
        Next
    End Sub

if you don't like the limit and have to ReDim your array then use a List.

 Dim grid As List(of PictureBox)
        Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
           grid=new list(of picturebox)
            For i = 0 To 48
                grid.add(New PictureBox)
                Me.Controls.Add(grid.item(grid.count-1))
            Next
        End Sub

edited Oct 31, 2017 at 0:50

answered Oct 31, 2017 at 0:17

user7452368

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6 Comments

user7452368 Over a year ago

it's not grid(i) that is nothing. it is grid() that is not initialized

RicRev Over a year ago

How is this any different from what I'm doing? You're just limiting the array size to 49.

user7452368 Over a year ago

you are asking for help. I gave you the answer in the comment on why your code isn't working. I'm not limiting the array. I'm initializing it

Joel Coehoorn Over a year ago

@RicRev He's not limiting the array size. He's giving it any size at all. Without the size, all you have is a variable reference that doesn't point to anything. If you're used to a language like javascript, where arrays are dynamic, those aren't real arrays in the formal computer science sense at all. They are collections with some array-like properties. Real arrays have a fixed size. But even this won't work. You also want to set a position for each PictureBox, or they'll all be stacked on top of each other at position (0, 0).

Joel Coehoorn Over a year ago

Oh, and VB.Net defines arrays using the index of the last item, not the number of items. So an array with 49 items (indexes from 0 to 48) is declared using a 48 subscript.

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