__ Dynamically allocate arrays when you don't know how many items to store!
All programmers need to allocate arrays to store data, and very often they don't know how much they will be storing. here is a beginners tutorial that shows how to dynamically allocate an array on the fly that will only allocate as many items as are needed!
Original Author: Fosters
Code
This is a short tutorial on dynamically building arrays
(with examples for 1 and 2 dimensions).
There are many occasions where you need
to allocate an array, but don't know what the upper bounds are.
Shown here is an efficient tried and trusted method.
The whole concept revolves around UBOUND - the upper limit of your array.
Knowing the upper limit allows you to increase it's size by as much as
you need to, without having to initially allocate a huge
array at the start!
The key points are
'define a 0 bounded array, so that redims later on do not fail
ReDim sTempArray(0)
'perform your loop to work out what must go in each element of your array
Do
If we need to allocate another item to the array Then
'redimension the array to accomodate the new data
ReDim Preserve sTempArray(UBound(sTempArray) + 1)
sTempArray(UBound(sTempArray) - 1) = ???
End If
Loop Until ???
'this method allocates 1 too many array items, so reduce it by 1
ReDim Preserve sTempArray(UBound(sTempArray) - 1)
'Array is ready to be returned with only the data you have allocated
You can paste the following example code to an app.
run your app, Pause it, and in the immediates window, type GetArrayData
Sub GetArrayData()
Dim sRecieve1DArray() As String
Dim sRecieve2DArray() As String
sRecieve1DArray = ReturnOneDimensionalArray
Debug.Print UBound(sRecieve1DArray) Debug.Print sRecieve1DArray(0), sRecieve1DArray(1), sRecieve1DArray(2)
sRecieve2DArray = ReturnTwoDimensionalArray
Debug.Print UBound(sRecieve2DArray, 2)
Debug.Print sRecieve2DArray(0, 0), sRecieve2DArray(0, 1), sRecieve2DArray(0, 2)
Debug.Print sRecieve2DArray(1, 0), sRecieve2DArray(1, 1), sRecieve2DArray(1, 2)
End Sub
Function ReturnOneDimensionalArray() As String()
Dim sTempArray() As String
Dim iCount As Integer
'initially define the array otherwise the other redims will fail
ReDim sTempArray(0)
iCount = 0
Do
'redimension the array to the upper limt + 1
ReDim Preserve sTempArray(UBound(sTempArray) + 1)
'populate into the upper limit -1
sTempArray(UBound(sTempArray) - 1) = Chr(65 + iCount)
iCount = iCount + 1
Loop Until iCount >=
26
'you have 1 more index than necessary, so reduce it by 1
ReDim Preserve sTempArray(UBound(sTempArray) - 1)
'assign the temporary array to the function for return
ReturnOneDimensionalArray = sTempArray
End Function
Function ReturnTwoDimensionalArray() As String()
Dim sTempArray() As String
Dim iCount As Integer
'initially define the array otherwise the other redims will fail
'remember, you can only redim the last dimension
ReDim sTempArray(2, 0)
iCount = 0
Do
'redimension the array to the upper limt + 1
'you are referencing and increasing the 2nd dimension
ReDim Preserve sTempArray(2, UBound(sTempArray, 2) + 1)
'populate into the upper limit -1
sTempArray(0, UBound(sTempArray, 2) - 1) = Chr(65 + iCount)
sTempArray(1, UBound(sTempArray, 2) - 1) = Chr(97 + iCount)
iCount = iCount + 1
Loop Until iCount >=
26
'you have 1 more index than necessary (on the 2nd dimension), so reduce it by 1
ReDim Preserve sTempArray(2, UBound(sTempArray, 2) - 1)
'assign the temporary array to the function for return
ReturnTwoDimensionalArray = sTempArray
End Function
Loading Comments ...
Comments
No comments have been added for this post.
You must be logged in to make a comment.