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Excel VBA ReDim Statement

The VBA ReDim statement is similar to the Dim statement. But, the difference is that one may use it to store or allocate more storage space or decrease the storage space a variable or an array has. Now, there are two important aspects used with the statement: Preserve. If one uses Preserve with this statement, it creates a new array with different sizes. But, on the other hand, if one does not use Preserve with this statement, it just changes the array size of the current variable.

Arrays are an important part of VBA coding. Using arrays, we can store more than one value in the same variable we defined. Like how we declare the variable using the word “Dim,” we need to declare the array name by using “Dim” as well.

To declare the array name, we need first to identify the kind of array we are going to define. In arrays, we have 5 types:

1. Static Array
2. Dynamic Array
3. One Dimensional Array
4. Two Dimensional Array
5. Multi-Dimensional Array

In the static array in excelArray formulas are extremely helpful and powerful formulas that are used in Excel to execute some of the most complex calculations. There are two types of array formulas: one that returns a single result and the other that returns multiple results.read more, we will decide the lower value and upper value of the array well in advance while declaring the variable. For example, look at the below example.

Code:

Sub ReDim_Example1()
  
  Dim MyArray(1 To 5) As String

End Sub

MyArray is the array’s name, which can hold the value from 1 to 5. So, for example, MyArray can hold 5 different results, like the one below.

Code:

Sub ReDim_Example1()
  Dim MyArray(1 To 5) As String

  MyArray(1) = "Hi"
  MyArray(2) = "Good"
  MyArray(3) = "Morning"
  MyArray(4) = "Have a"
  MyArray(5) = "Nice Day"

End Sub

Dynamic Array with ReDim Statement

But in the dynamic array, this is not the case. Therefore, we will not decide on the lower and upper values well in advance. Rather, we define the array name and assign data type.

Sub ReDim_Example1()

Dim MyArray() As String

End Sub

To make the array name dynamic, we need to declare it with the word “Dim” first, but don’t decide the array size well in advance. Instead, we name an array with empty values inside the parenthesis (). When the array does not include size, it treats it as a dynamic array.

Dim MyArray() As String

When you mention the array size inside the parenthesis, it becomes a static array. Dim MyArray(1 to 5) As String.

In the dynamic array, we always resize the array size by using the word “ReDim” in the next line of the code.

ReDim MyArray(1 to 6) As String

Any value stored to the array name in the previous steps, i.e., using the “Dim” statement, stands null, and the size we declared using “ReDim” becomes the new size of the array.

Examples to use VBA Redim Statement

You can download this VBA ReDim Excel Template here – VBA ReDim Excel Template

Example #1

Look at the example of using the “ReDim” statement practically. Then, follow the below steps to apply “ReDim.”

Step 1: Create a macro name first.

Step 2: Declare an array name as a string.

Code:

Sub ReDim_Example1()

  Dim MyArray() As String

End Sub

Step 3: Now, use “Redim” and assign the array size.

Code:

Sub ReDim_Example1()

  Dim MyArray() As String
  ReDim MyArray(1 To 3)

End Sub

Step 4: The array name “MyArray” can hold up to 3 values here. Assign the value to these 3 arrays like the below one.

Code:

Sub ReDim_Example1()

  Dim MyArray() As String
  ReDim MyArray(1 To 3)

  MyArray(1) = "Welcome"
  MyArray(2) = "to"
  MyArray(3) = "VBA"

End Sub

So, the first array is equal to the word “Welcome,” and the second is equal to the word “to.” Finally, the third array is equal to the word “VBA.”

Step 5: Now, store these array values in cells.

Code:

Sub ReDim_Example1()

  Dim MyArray() As String
  ReDim MyArray(1 To 3)

  MyArray(1) = "Welcome"
  MyArray(2) = "to"
  MyArray(3) = "VBA"

  Range("A1").Value = MyArray(1)
  Range("B1").Value = MyArray(2)
  Range("C1").Value = MyArray(3)

End Sub

Step 6: If you run this code, we should have these values in A1, B1, and C1 cells, respectively.

Example #2 – Resize the Array Size While Remembering the Old Values.

Once the array name is assigned values, we can resize it at any point in the procedure by using the word “ReDim Preserve.”

Assume you have already declared an array name and assigned values to those array names like the below one.

Now, you would like to increase the array length by 2, i.e., 5. In this case, we can use the word VBA “ReDim Preserve” to resize the array length and remember the old values.

Code:

Sub ReDim_Example2()
  
  Dim MyArray() As String
  ReDim MyArray(3)

  MyArray(1) = "Welcome"
  MyArray(2) = "to"
  MyArray(3) = "VBA"

  ReDim Preserve MyArray(4)
  MyArray(4) = "Character 1"

  Range("A1").Value = MyArray(1)
  Range("B1").Value = MyArray(2)
  Range("C1").Value = MyArray(3)
  Range("D1").Value = MyArray(4)

End Sub

Now, we can assign two more values to the array.

Code:

Sub ReDim_Example2()

  Dim MyArray() As String
  ReDim MyArray(3)

  MyArray(1) = "Welcome"
  MyArray(2) = "to"
  MyArray(3) = "VBA"

  ReDim Preserve MyArray(4)
  MyArray(4) = "Character 1"

  Range("A1").Value = MyArray(1)
  Range("B1").Value = MyArray(2)
  Range("C1").Value = MyArray(3)
  Range("D1").Value = MyArray(4)

End Sub

Now, store these values in cells.

Code:

Sub ReDim_Example2()

  Dim MyArray() As String
  ReDim MyArray(3)

  MyArray(1) = "Welcome"
  MyArray(2) = "to"
  MyArray(3) = "VBA"

  ReDim Preserve MyArray(4)
  MyArray(4) = "Character 1"

  Range("A1").Value = MyArray(1)
  Range("B1").Value = MyArray(2)
  Range("C1").Value = MyArray(3)
  Range("D1").Value = MyArray(4)

End Sub

Now, run the Macro and see what happens.

So, we got the new word in the D1 cell.

We need to use the word “Preserve” because the array should remember the old array values in the procedure.

When you ignore the word “Preserve,” it will not remember old values.

Things to Remember Here

• The ReDim can only hold the last value of the array, not the many values. So, for example, we cannot use the code “ReDim Preserve MyArray(4 to 5)”. Instead, it will throw an error.
• We cannot ReDim static arrays. When you assign the array size inside the parenthesis, it becomes a static array.
• Using ReDim, we cannot change the data type. The array can hold whatever data type we have assigned while declaring the array.

Recommended Articles

This article has been a guide to VBA ReDim. Here, we discuss handling dynamic arrays using ReDim Preserve, examples, and a downloadable Excel template. Below are some useful Excel articles related to VBA: –

• VBA ISNULL
• VBA Format
• Delete Row in VBA
• Excel VBA Subscript Out of Range
• VBA Max

This tutorial will demonstrate how to use dynamic arrays (redim and redim preserve) in VBA.

Dynamic Array

Dynamic Arrays are arrays that can change sizes (as opposed to static arrays, which are static).

To declare a dynamic array, you declare the array, but omit the array size:

Dim strNames() As String

Then, before you can assign values to your array, you must use the ReDim Statement to set the array to your desired size:

ReDim strNames(1 to 3)

Now, anytime you want to change your array size, simply use ReDim (or ReDim Preserve as we’ll learn about below).

Dynamic Variant Arrays

Note: Variant Arrays are a little different. With variant arrays, you don’t need to set the array size with ReDim before assigning values.

Sub TestArray()
'declare the variable
    Dim varNames() As Variant
'populate the array
    varNames() = Array("Fred", "Wilma", "Barney", "Betty")
'return the values
    MsgBox Join(varNames, ",")
End Sub

Redim vs. Redim Preserve

The ReDim statement resizes an array, clearing all existing values.

The ReDim Preserve statement resizes an array, keeping (“preserving”) all existing values.

Using ReDim

In practice, resizing an array with ReDim looks like this:

Sub TestReDim()
'declare the string array
   Dim strNames() As String
'resize the string array to be able to hold 3 values
   ReDim strNames(1 to 3)
'populate the array with 3 names
   strNames(1) = "Mel"
   strNames(2) = "Steve"
   strNames(3) = "Bob"
'show the result in the immediate window
   Debug.Print Join(strNames, vbCrLf)
End Sub

Using ReDim Preserve

In this example, we will use ReDim to set the initial dynamic array and then ReDim Preserve to resize the array, keeping the original values:

Sub TestReDim()
'declare the string array
   Dim strNames() As String
'resize the string array to be able to hold 3 values
   ReDim strNames(1 to 3)
'populate the array
   strNames(1) = "Mel"
   strNames(2) = "Steve"
   strNames(3) = "Bob"
'show the result in the immediate window
   Debug.Print Join(strNames, vbCrLf)
'redim but preseve the data
   ReDim Preserve strNames(1 to 4)
   strNames(4) = "Fred"
'show the result in the immediate window
   Debug.Print Join(strNames, vbCrLf)
End Sub

If you do not use the PRESERVE statement, you would lose the data that had been in the array previously.

In the  immediate window above, the array populated Mel, Steve and Bob.  When it was re-declared, it remove those values and instead returned 3 blank values and then the value ‘Fred’.   This is due to the PRESERVE statement being omitted.