VBA Loops + Arrays

I still don't think you're there with your title - try something that describes the problem, "Help understanding arrays", perhaps.

To answer your main question an array is a variable which has multiple elements, referenced by an index number (or numbers, but let's not go there yet).

So, for example, if I wanted to write a VBA program to ask for three numbers I could code this...

Dim GetNumber1, GetNumber2, GetNumber3

GetNumber1=InputBox("Please enter number 1")
GetNumber2=InputBox("Please enter number 2")
GetNumber3=InputBox("Please enter number 3")

That would work, but if I wanted to get 10 numbers, or 100, or even more it would get very, very long-winded and be hard to work with, so I could define an array, like so...

Const HowManyNumbers=3

Dim GetNumber(HowManyNumbers), GetNumberIndex

For GetNumberIndex=1 To HowManyNumbers
  GetNumber(GetNumberIndex)=InputBox("Please enter number " & GetNumberIndex)
Next GetNumberIndex

Functionally these two programs are identical, but the second one can be expanded to allow for the input of any number of numbers, just by changing the value assigned to HowManyNumbers.

All of the numbers input are stored in the array GetNumber, but each one is stored in a unique element of that array, referenced by number, so if I wanted to output the first number entered I could say

MsgBox GetNumber(1)

More importantly I can deal with the numbers one at a time by putting them inside a For...Next loop, so I could output the numbers in the order they were entered with the code...

For i=1 to 3
  MsgBox GetNumber(i)
Next i

Arrays are absolutely essential to efficient coding, because they allow you to deal with sets of values, rather than having to reference each one individually. I don't mean to be rude, but if you're taking a VBA course shouldn't they be teaching you this sort of thing?

You need to put your code in code tags, or you'll be in more trouble.

As this is an assignment I think it would be wrong for me to just give you the answer, but I've put a few comments in your code...

Private Sub CommandButton1_Click()
Dim Arr(3) As Integer

Arr(0) = Mid(TextBox1, 1, 1)
Arr(1) = Mid(TextBox1, 2, 1)
Arr(2) = Mid(TextBox1, 3, 1)
Arr(3) = Mid(TextBox1, 4, 1) 'This whole section could be done in a loop

For Arr = 0 To 3
Arr (0) + 7 'This line doesn't do anything because it's not assigning the value to anywere, you also need to look at the Mod function (as per the requirements)
Next

Loop 'Which loop?
TextBox2.value = Arr(2) & Arr(3) & Arr(0) & Arr(1)

Changed my thread title and depicted the code properly. I am having trouble understand what loop to make for this and how to make it Mod10 as it says in the project description. basically the encrypted number is supposed to be 4 digits just like the encrypted one, so adding 7 to a number higher than 3 gives you a two digit number and that will not work.

Gahhh this may be close, but still wrong. Any help is greatly appreciated!

Dim encrypt(3) As Integer

    encrypt(0) = Mid(TextBox1, 1, 1)
    encrypt(1) = Mid(TextBox1, 2, 1)
    encrypt(2) = Mid(TextBox1, 3, 1)
    encrypt(3) = Mid(TextBox1, 4, 1)
    
    For encrypt(0 to 3)
    Arr(LoopVar) = (Arr(LoopVar) + 7) Mod 10
    Next
    
    
    'Arr(0) = Arr(0) + 7
    'Arr(1) = Arr(1) + 7
    'Arr(2) = Arr(2) + 7
    'Arr(3) = Arr(3) + 7
    
    
    
    TextBox2.value = Arr(2) & Arr(3) & Arr(0) & Arr(1)

What do I need to change