Excel do while function

Организация выполнения повторяющихся действий в VBA может быть выполнена несколькими операторами, которые условно разделяют на цикл-пока, цикл-до, цикл-для.

Оператор While

Общий вид оператора While:

While выражение
[инструкции]
Wend

Оператор While предназначен для организации цикла-пока.

Инструкции будут выполняться пока выражение будет истинно.

Пример. Вычислить сумму чисел от 0 до 100.

Решение.

Sub сумма1()
Dim x, s As Double
 
x = 0
s = 0
While x <= 100
s = s + x
x = x + 1
Wend
MsgBox ("s=" + Str(s))
 
End Sub

Пояснение решения.

В переменной s накапливается значение суммы.

Оператор Do While

Общий вид оператора Do While:

Do [While выражение]
[инструкции]
[Exit Do]
[инструкции1]
Loop

Оператор Do While предназначен для организации цикла-пока.

Инструкции будут выполняться пока выражение будет истинно. Конструкция Exit Do предназначена для преждевременного выхода из цикла.

Пример. Вычислить сумму чисел от 0 до 100.

Решение.

Sub сумма2()
Dim x, s As Double
 
x = 0
s = 0
 
Do While x <= 100
s = s + x
x = x + 1
Loop
 
MsgBox ("s=" + Str(s))
 
End Sub

Оператор Do Loop Until

Общий вид оператора Do Loop Until:

Do
[инструкции]
[Exit Do]
[инструкции1]
Loop [Until выражение]

Оператор Do Loop Until предназначен для организации цикла-до.

Инструкции будут выполняться до момента, когда выражение станет истинным. Конструкция Exit Do предназначена для преждевременного выхода из цикла.

Пример. Вычислить сумму чисел от 0 до 100.

Решение.

Sub сумма3()
Dim x, s As Double
x = 0
s = 0
 
Do
s = s + x
x = x + 1
Loop Until x > 100
 
MsgBox ("s=" + Str(s))
 
End Sub

Оператор For

Общий вид оператора For:

For счетчик = начальное_знач To конечное_знач [Step шаг]
[инструкции]
[Exit For]
[инструкции1]
Next [счетчик]

Оператор For предназначен для организации цикла-для.

Инструкции будут выполняться определенное количество раз, задаваемое в счетчик, начиная с начального значение (начальное_знач) до конечного значения (конечное_знач) с некоторым шагом (шаг). Конструкция Exit For предназначена для преждевременного выхода из цикла.

Пример. Вычислить сумму чисел от 0 до 100.

Решение.

Sub сумма4()
Dim x, s As Integer
 
s = 0
For x = 0 To 100
s = s + x
Next x
 
MsgBox ("s=" + Str(s))
 
End Sub

Примеры решения задач

Пример 1. Представить таблицу квадратов чисел от 2 до 10.

Решение.

Для отображения результатов воспользуемся Excel и для доступа к ячейкам функцией Cells (номер_строки, номер_колонки).

Sub квадраты()
Dim x
 
Cells(2, 1).Value = "x"
Cells(3, 1).Value = "x^2"
 
For x = 2 To 10
Cells(2, x).Value = x
Cells(3, x).Value = x ^ 2
Next x
End Sub

Пример 2

Пример 2. Составить программу определения наибольшего общего делителя (НОД) двух натуральных чисел.

Решение.

Наибольший общий делитель двух натуральных чисел — это самое большое натуральное число, на которое они делятся. Например, у чисел 12 и 18 наибольшие делители: 2, 3, 6. наибольшим общим делителем является число 6. Это записывается так:

НОД(12, 18) = 6.

Идея алгоритма Евклида для нахождения НОД основана на том свойстве, что если M>N, то

НОД(M, N) = НОД(M-N, N).

Иначе говоря, НОД двух натуральных чисел равен НОД их положительной разности и меньшего числа.

Sub Евклид()
Dim M, N, NOD
 
M = Cells(1, 2)
N = Cells(2, 2)
 
While M <> N
 
If M > N Then
M = M - N
Else
N = N - M
End If
Wend
 
NOD = M
Cells(3, 2).Value = NOD
 
End Sub

Пример 3

Пример 3. Построить график функции: улитку Паскаля.

Улитка Паскаля задается следующим образом:

x=A*cos(t)+B*cos(t)
y=A*cos(t)sin(t)+B*sin(t), A>B, B>0, 0<=t<2*Pi

Решение.

1. Подготовить данные в электронной таблице

2. Ввести код программы.

Sub улитка_паскаля()
 
Dim a, b, Pi, t As Double
Dim i As Integer
 
a = Cells(1, 2)
b = Cells(2, 2)
Pi = 3.14
i = 2
t = 0
 
While t <= 2 * Pi
x = a * Cos(t) + b * Cos(t)
y = a * Cos(t) * Sin(t) + b * Sin(t)
 
Cells(3, i).Value = x
Cells(4, i).Value = y
t = t + 0.1
i = i + 1
Wend
 
End Sub

3. Построить график с помощью мастера диаграмм, выбрав точечную диаграмму.

4. Изменить данные a и b.

A=2
B=1

5. Перезапустить макрос.

Loops are used in VBA for repeating a set of statements multiple times. Loops form an essential part of any programming language, and VBA is no exception. There are five different types of loops that can be used in VBA. These are as follows:

• For Loop
• For Each Loop
• Do While Loop
• Do Until Loop
• Wend Loop (obsolete)

In this post, I will explain all these VBA Loops with examples. But before jumping into the topic, let’s understand what a loop is and why it is used.

What is a loop, and what are its uses?

Loop is an instruction that can continually repeat a set of statements until a particular condition is reached.

Loops can serve the following purposes:

• It helps in iterating a set of statements.
• It helps in checking a particular condition multiple times.
• It can also help in developing custom sleep and wait logic in code.

VBA FOR LOOP

For loop is one of the most important and frequently used loop in VBA. For Loop is sometimes also called ‘For Next Loop’.

For Loops allow you to iterate a set of statements for a specified number of times.

Syntax of VBA For Loop

The basic syntax of a VBA For loop or structure of For Loop is as follows:

For loop_ctr = start_num To end_num [step_increment]
'Statements to be executed inside the loop
Next loop_ctr

How does a VBA For Loop Work?

Let’s say we have a simple For Loop in VBA as shown below:

For loop_ctr = 1 To 100
'Statements to be executed inside the loop
Next loop_ctr

• When the program control reaches the statement ‘For loop_ctr = 1 To 100’, it reserves a space for the variable ‘loop_ctr’ in the memory and initializes it to 1.
• After this, it executes the statements inside the For Loop sequentially.
• Finally, the program control reaches the statement ‘Next loop_ctr’, here it increments the variable ‘loop_ctr’ by 1. And the control again goes to the statement ‘For loop_ctr = 1 To 100’, where it checks if the value of ‘loop_ctr’ has reached 100 or not. If the value is less than 100, then it continues the next iteration; otherwise, the loop stops.

Still not clear with the working of a For Loop? No Worries. Let’s try to understand this with the help of a flow diagram.

VBA For Next Loop Flow Diagram

Let’s try to understand the control flow as depicted in the above flow chart:

1. First of all, the FOR statement is executed. This step allows the ‘loop_ctr’ and ‘step_increment’ values to be initialized.
2. After this, the condition is evaluated. If the condition is TRUE, all the statements inside the loop ‘Code Block’ are executed. However, If the condition evaluates to FALSE, then the control flow jumps to the next statement outside the For loop.
3. When the ‘code block’ inside the For Loop executes, the loop starts to get ready for the next iteration and increments the ‘loop_ctr’ value.
4. Finally, the condition is again evaluated with the incremented ‘loop_ctr,’ and the process repeats itself.

Few Simple Examples of For Loop In VBA

Let’s see some simple examples of For Loop in VBA.

Example 1: Use VBA For Loop to print numbers from 1 to 10 in excel.

In this example, we have a range «A1:A10”, and we have to fill this range with numbers from 1-10.
To accomplish this, we can use the below code:

Sub ForLoopPrintNumbers()
Dim loop_ctr As Integer
For loop_ctr = 1 To 10
ActiveSheet.Range("A1").Offset(loop_ctr - 1, 0).Value = loop_ctr
Next loop_ctr
MsgBox "For Loop Completed!"
End Sub

Explanation:

In the above code, first of all, we have declared the loop counter ‘loop_ctr’ for our For loop. Next, along with the For statement, we have initialized the ‘loop_ctr’ to 1 and set the ‘end_num’ as 10.

Inside the For Loop body, we have written the code to write the loop_ctr value on the excel sheet in the A column. After this, there is a statement that increments the ‘loop_ctr’ for the next iteration.

Note that since we have not specified an explicit ‘step_increment’ value, so every iteration, the ‘loop_ctr’ will be incremented by 1. The For loop in the above code iterates 10 times and populates the cells in the range A1:A10 with numbers from 1-10 serially.

Example 2: Use For Loop in VBA to find the sum of all the numbers between 1 to 10.

In this example, we will loop through all the numbers between 1 to 10 and sum them. Finally, we will be displaying the sum of the numbers from 1 to 10 on the screen.

To do this we can use the following code:

Sub ForLoopSumNumbers()
Dim loop_ctr As Integer
Dim result As Integer
result = 0
For loop_ctr = 1 To 10
result = result + loop_ctr
Next loop_ctr
MsgBox "Sum of numbers from 1-10 is : " & result
End Sub

Explanation:

In the above code, first of all, we have declared the loop counter ‘loop_ctr’ for our For loop. Next, we have declared another integer variable as ‘result’ for storing the sum of numbers from 1 to 10.

After this, along with the For statement, we have initialized the ‘loop_ctr’ to 1 and set the ‘end_num’ as 10.

Inside the For Loop body, we have added the value of ‘loop_ctr’ along with the result. This means that in the first iteration, the result will be: 1, and in the second iteration, it will be : (1+2) = 3. Similarly, in the third iteration, the value will be: (3 + 3) = 6 and so on.

After the For loop body, there is a statement that increments the ‘loop_ctr’ for the next iteration.

Note that since we have not specified an explicit ‘step_increment’ value, hence with every iteration, the ‘loop_ctr’ will be incremented by 1.

The For loop in the above code iterates 10 times and sums all the numbers from 1 to 10, and finally displays the sum of these numbers in msgbox.

Example 3: Use VBA For Loop to print numbers, all even numbers from 1 to 10.

In this example, we will fill all the even numbers between 1 and 10 into cells A1 to A5.

To do this, we can use the below code:

Sub ForLoopToPrintEvenNumbers()
Dim loop_ctr As Integer
Dim cell As Integer
cell = 1
For loop_ctr = 1 To 10
If loop_ctr Mod 2 = 0 Then
ActiveSheet.Range("A1").Offset(cell - 1, 0).Value = loop_ctr
cell = cell + 1
End If
Next loop_ctr
MsgBox "For Loop Completed!"
End Sub

Explanation:

In the above code, first of all, we have declared the loop counter ‘loop_ctr’ for our For loop. After that, we have declared another variable ‘cell’. This variable is initialized with a value of 1.

Next, along with the For statement, we have initialized the ‘loop_ctr’ to 1 and set the ‘end_num’ as 10.

Inside the For Loop body, we have used an IF statement to check if the ‘loop_ctr’ value is even or not.

If the ‘loop_ctr’ value is Even then, we have written a statement to print the value out to the spreadsheet in the A column.

After this, we are incrementing the cell variable by 1. We have used the cell variable in our loop to print the values in the appropriate cell in the A column.

Next, there is a statement that increments the ‘loop_ctr’ for the next iteration.

Note that since we have not specified an explicit ‘step_increment’ value, after every iteration, the ‘loop_ctr’ will be incremented by 1.

The For loop in the above code iterates 10 times and populates the cells in the range A1:A5 with even numbers from 2-10.

Alternate Logic

There is another better way to accomplish the same, let’s see how.

Sub ForLoopToPrintEvenNumbers()
Dim loop_ctr As Integer
Dim cell As Integer
cell = 1
For loop_ctr = 2 To 10 Step 2
ActiveSheet.Range("A1").Offset(cell - 1, 0).Value = loop_ctr
cell = cell + 1
Next loop_ctr
MsgBox "For Loop Completed!"
End Sub

Explanation:

In the above code, we have looped through all the numbers between 2 to 10. Instead of the default ‘step_increment’ of 1, we are using an explicit ‘step_increment’ of 2.

In the first iteration of the for loop, the ‘loop_ctr’ value is 2, which is what gets printed in cell A1. In the second iteration, the ‘loop_ctr’ value becomes 4 (earlier value : 2 + step_increment : 2) and this number gets printed on cell A2.

Similarly, in the third iteration, the ‘loop_ctr’ value is 6 (earlier value: 4 + step_increment: 2) and it gets printed on the cell A3 and so on.

Writing a Nested For Loop

There are times when you might need to use a for loop within another for loop; this is called nesting of for loops.

VBA For loops can be nested within one another to perform complex tasks in excel. Let’s understand a nested loop with an example:

Example 4: Print numbers from 1 to 10 in all the worksheets in an excel spreadsheet using a For Loop.

In this example, we need to print numbers from 1 to 10 in all the worksheets in an excel workbook.

To do this, we can make use of the following code:

Sub ForLoopPrintNumbers()
Dim loop_ctr As Integer
Dim sheet As Integer
For sheet = 1 To Worksheets.Count
For loop_ctr = 1 To 10
Worksheets(sheet).Range("A1").Offset(loop_ctr - 1, 0).Value = loop_ctr
Next loop_ctr
Next sheet
MsgBox "For Loop Completed!"
End Sub

Explanation:

In this example, there are two For Loops, one inside another. The Outer For Loop iterates over the variable ‘sheet’, and the Inner For Loop iterates over ‘loop_ctr’ that determines the cell position.

Inside the body of the Inner For loop, we have a statement that prints the numbers between 1 to 10 in each worksheet (as per the outer loop).

The outer loop iterates over all the available sheets in the spreadsheet, whereas the inner loop iterates over the A1 to A10 for the current sheet. This makes it possible to print numbers from 1 – 10 in all the available worksheets.

Reverse For Loop in VBA

In all our previous examples, we have only seen those For loops in which the loop counter variable gets incremented from a lower value to a higher value (with each iteration).

But this is not necessary, you can also have a For Loop where the loop counter moves from a higher value to a lower value (with each iteration).

Example 5: Use a Reverse For Loop to print numbers from 1 to 10 in descending order.

Sub ReverseForLoop()
Dim loop_ctr As Integer
Dim cell As Integer
cell = 1
For loop_ctr = 10 To 1 Step -1
ActiveSheet.Range("A1").Offset(cell - 1, 0).Value = loop_ctr
cell = cell + 1
Next loop_ctr
MsgBox "For Loop Completed!"
End Sub

Explanation:

In this example, the loop starts with the value of ‘loop_ctr’ as 10. And then, with each iteration, the value of the loop counter is decremented by 1 (since the ‘step_increment’ is -1).

Inside the For Loop body, we print the value of the loop counter variable in the active sheet from A1:A10.

Infinite Loop Using a For Loop

An infinite loop is also sometimes called an Endless Loop. An Infinite Loop is a loop whose ending condition (often due to a logic error by the programmer) never becomes true. The loop iterates an infinite number of times or until halted by programmer/user action.

Although in the case of FOR loop, generally due to the clear start and end conditions, it is not easy to make an endless loop by logical mistake. However, there can be cases where you can by mistake reset the loop counter variable inside the loop, thereby making the loop infinite.

Below is an example of an endless for loop:

'Do not run this code
Sub InfiniteForLoop()
Dim loop_ctr As Integer
Dim cell As Integer
For loop_ctr = 1 To 10
ActiveSheet.Range("A1").Offset(loop_ctr - 1, 0).Value = loop_ctr
loop_ctr = loop_ctr - 1
Next loop_ctr
MsgBox "For Loop Completed!"
End Sub

The statement ‘loop_ctr = loop_ctr – 1’ makes the above VBA loop infinite since it resets the value of the loop_ctr with every iteration, and hence the end condition is never reached.

Tip: It is always good to not make any changes to the loop counter variable value inside the loop body.

How to Break Out or Exit of a For Loop

I believe many of you will wonder, «Why do we need to break a loop during execution»? The answer is simple: Breaking or exiting a loop can sometimes optimize the code and reduce the resource overhead.

To break a For Loop we can use the ‘Exit For’ statement.

Let’s try to see this in action with an example:

Example 6: Use a FOR loop in VBA to find the sum of the first 20 odd numbers between 1 to 100.

In this example, we have to find the first 20 odd numbers from 1 to 100 and then calculate their sum. Below is the code to do this:

Sub SumFirst20OddNumbers()
Dim loop_ctr As Integer
Dim odd_number_counter As Integer
Dim sum As Integer
For loop_ctr = 1 To 100
If (loop_ctr Mod 2 <> 0) Then
sum = sum + loop_ctr
odd_number_counter = odd_number_counter + 1
End If
If (odd_number_counter = 20) Then
Exit For
End If
Next loop_ctr
MsgBox "Sum of top 20 odd numbers is : " & sum
End Sub

Explanation:

In this example, we have three variables – ‘loop_ctr’, ‘odd_number_counter’, and ‘sum’. The variable ‘loop_ctr’ is used as a loop counter, the ‘odd_number_counter’ variable holds the count of odd numbers that have been summed (because we only need to sum the first 20 odd numbers), and the ‘sum’ variable holds the sum of the first 20 odd numbers.

Inside the loop, we iterate all the numbers from 1 to 100, one by one (step_increment is 1 as default), and check if the number is odd. If the number is odd, we sum it and increment the ‘odd_number_counter’ by 1.

After the first IF block, another IF condition checks if the ‘odd_number_counter’ variable value is 20. If the value of ‘odd_number_counter’ is 20, then using the ‘Exit For’ statement, we are exiting out of the loop as there is no point in continuing the loop further.

Few Practical Examples of VBA For Loop

Now let’s have a look at some of the practical examples where For Loop can be used:

Example 7: Highlight alternate rows on a spreadsheet using the VBA For Loop.

In this example, we need to highlight alternate rows in a spreadsheet. To do this we can use the below code:

Sub HighlightAlternateRows()
Dim loop_ctr As Integer
Dim Max As Integer
Dim clm As Integer
Max = ActiveSheet.UsedRange.Rows.Count
clm = ActiveSheet.UsedRange.Columns.Count
For loop_ctr = 1 To Max
If loop_ctr Mod 2 = 0 Then
ActiveSheet.Range(Cells(loop_ctr, 1), Cells(loop_ctr, clm)).Interior.ColorIndex = 28
End If
Next loop_ctr
MsgBox "For Loop Completed!"
End Sub

Explanation:

In the above code, we have started the loop from 1 to the number of rows in our sheet. We are then using the if statement to find the even-numbered rows for highlighting them.

Example 8: Use VBA For Loop Protect all sheets in Workbook.

In this example, we will try to create a VBA macro that loops through all the worksheets in the active workbook and protects all the worksheets.

Below is the code to do this:

Sub ProtectWorksheets()
Dim loop_ctr As Integer
For loop_ctr = 1 To ActiveWorkbook.Worksheets.Count
Worksheets(loop_ctr).Protect
Next loop_ctr
End Sub

Explanation:

In the above code, we are using a VBA for loop and iterating over all the worksheets in the open workbook. Inside the For Loop, we are trying to protect the current instance of the worksheet.

The above code can also be used to unprotect the sheets as well. Just replace the ‘Worksheets(loop_ctr).Protect’ with ‘Worksheets(loop_ctr).UnProtect’.

Example 9: Loop Over an Array of Numbers and Find the Largest and Smallest Numbers from the Array.

In this example, we have an array of numbers, and using a FOR Loop we have to iterate the array and find the smallest and the Largest numbers from the array. Below is the code to do this:

Sub ForLoopWithArrays()
Dim arr() As Variant
arr = Array(10, 12, 8, 19, 21, 5, 16)
Dim min_number As Integer
Dim max_number As Integer
min_number = arr(0)
max_number = arr(0)
Dim loop_ctr As Integer
For loop_ctr = LBound(arr) To UBound(arr)
If arr(loop_ctr) > max_number Then
max_number = arr(loop_ctr)
End If
If arr(loop_ctr) < min_number Then
min_number = arr(loop_ctr)
End If
Next loop_ctr
MsgBox "Largest Number: " & max_number _
& " Smallest Number: " & min_number
End Sub

Explanation:

In the above code, we have an array of numbers declared as ‘arr’ variable. In addition to that, we have two variables, ‘min_number’ and ‘max_number’, that are used for holding the minimum and maximum numbers from the array.

We initialize both the ‘min_number’ and ‘max_number’ variables to the array’s first element. Next, inside the For loop, we loop through all the array elements and check –

If the current number is greater than the ‘max_number’, then set the ‘max_number’ value equal to the current number. The next condition that we check is – If the current number is less than the ‘min_number’, then set the ‘min_number’ value equal to the current number.

Finally, we are showing the largest and the smallest numbers inside the array with the help of a msgbox.

VBA For Each Loop

For each is a more sophisticated type of For Loop. It can be used for iterating a collection of objects.

Here you don’t have to worry about the loop counter, your job is to simply pass a collection of objects, and the loop itself identifies the objects and iterates them.

Syntax of a VBA For Each Loop

The syntax of For Each Loop resembles closely to For Loop. Below is the syntax:

For Each item In collection_of_items
'Statements to be executed inside the loop
Next item

Here, ‘collection_of_items’ refers to a group of objects that you need to iterate. If you supply a single object to this parameter, it throws a «run-time error 438».

‘item’ specifies the objects inside the ‘collection_of_items’. At any particular instant inside the loop, ‘item’ contains a single object from the ‘collection_of_items’.

How a For Each Loop Works

Let’s say we have a For Each Loop as:

For Each cl In ActiveSheet.Range("A1:A10")
'Statements to be executed inside the loop
Next cl

• When the program control reaches the statement ‘For Each cl In ActiveSheet.Range(«A1:A10»)’ it evaluates the object collection and then initializes the variable ‘cl’ with the first object in the collection, i.e., cell $A$1.
• After this, it executes the statements inside the loop.
• Next, it fetches the second object from the collection and dumps it in the variable ‘cl’. And the process continues till it has fetched all objects from the collection.

Flow Diagram of a For Each Loop In VBA

Let’s try to understand the control flow as depicted in the above flow chart:

1. First of all, the FOR EACH statement is executed and checks if there are any elements in the collection.
2. If there are any elements present in the collection, the ‘item’ variable is initialized to the first element of the collection, and the statements inside the loop ‘Code Block’ is executed. However, If the condition evaluates to FALSE, then the control flow jumps to the next statement outside the For Each loop.
3. When the ‘code block’ inside the For Each Loop executes, the loop starts to get ready for the next iteration. The ‘item’ variable is re-initialized to the next element in the collection, and the loop continues.

Few Simple Examples of VBA For Each Loop

Now let’s move to some simple examples of For Each loop.

Example 1 – Use VBA For Each Loop to display the names of all the Active Worksheets.

In this example, we will use a For Each loop to iterate through all the worksheets in the ActiveWorkbook and display the names of all the sheets using a msg box.

Sub ForEachDisplaySheetNames()
Dim sheetNames As String
For Each sht In ActiveWorkbook.Sheets
sheetNames = sheetNames & vbNewLine & sht.Name
Next sht
MsgBox "The Sheet names are : " & vbNewLine & sheetNames
End Sub

Explanation:

In this example, the For Each loop takes the collection of sheets from ‘ActiveWorkbook.Sheets’ it then iterates the sheets one by one and initializes the ‘sht’ variable with the current sheet instance.

Inside the For Each block, the sheet name for each worksheet is appended to a string, and finally, outside the loop, all the sheet names are displayed using a message box.

Example 2: Use VBA For Each Loop to Sum all the Elements of an Array.

In this example, with the help of a VBA For Each loop, we will be iterating an array of numbers and find the sum of all of its elements. Below is the code to do this:

Sub ForEachSumArrayElements()
Dim arr As Variant
Dim sum As Integer
arr = Array(1, 10, 15, 17, 19, 21, 23, 27)
For Each element In arr
sum = sum + element
Next element
MsgBox "The Sum is : " & sum
End Sub

Explanation:

In the above code, we have declared two variables, ‘arr’ and ‘sum’. The ‘arr’ variable is used for storing the array of numbers, and the ‘sum’ variable represents the sum of the array elements.

Inside the For Each loop, we are iterating the array elements one by one, summing them up, and storing the total in the ‘sum’ variable.

Finally, outside the For Each loop, we show the sum of the array elements using a message box.

Example 3: Use VBA For Each Loop to display the names of all the Open Workbooks.

In this example, using a For Each loop, we will loop through all the open workbooks and display their name using a message box.

Below is the code to do this:

Sub ForEachDisplayWorkbookNames()
Dim workBookNames As String
For Each wrkbook In Workbooks
workBookNames = workBookNames & vbNewLine & wrkbook.Name
Next wrkbook
MsgBox "The Workbook names are : " & vbNewLine & workBookNames
End Sub

Explanation:

In this example, the For Each loop takes the collection of workbooks, then iterates the workbooks one by one and initializes the ‘wrkbook’ variable with the current workbook instance.

Inside the For Each block, the workbook name for each workbook is appended to a string, and finally, outside the loop, all the workbook names are displayed using a message box.

Nested VBA For Each Loop

Two For Each loops can be nested within one another to perform complex tasks. Let’s understand For Each nested loop with an example:

Example 4: Display the names of all open workbooks along with their corresponding worksheets.

In this example, we will be iterating through all the open workbooks and then iterate through each workbook’s worksheets and finally display them using a message box.

Below is the code to do this:

Sub ForEachLoopNesting()
Dim result As String
For Each wrkbook In Workbooks
For Each sht In wrkbook.Sheets
result = result & vbNewLine & " Workbook : " & wrkbook.Name & " Worksheet : " & sht.Name
Next sht
Next wrkbook
MsgBox result
End Sub

Explanation:

In the above code, we have used two For Each loops, one inside another. The outer For Each loop iterates through the workbooks, and the inner For Each loop iterates through the worksheets.

Inside the inner For Each block, a statement concatenates the names of the workbooks and the worksheets and stores them in a variable called ‘result’.

With each iteration, the ‘result’ variable’s new value is appended to the existing value. Finally, the value of the ‘result’ variable is displayed inside a msgbox.

How to Break Out or Exit of a For Each Loop

To break out of a For Each loop, we can use the ‘Exit For’ statement. So, ‘Exit For’ statement can break both a For loop as well as a For Each loop.

Let’s see this with an example:

Example 5: Use VBA For Each Loop to display the names of the first 3 sheets in the active workbook.

In this example, we will loop through the worksheets inside the active workbook and only display the first 3 worksheet names. Below is the code to do this:

Sub ForEachDisplayFirstThreeSheetNames()
Dim sheetNames As String
Dim sheetCounter As Integer
For Each sht In ActiveWorkbook.Sheets
sheetNames = sheetNames & vbNewLine & sht.Name
sheetCounter = sheetCounter + 1
If sheetCounter >= 3 Then
Exit For
End If
Next sht
MsgBox "The Sheet names are : " & vbNewLine & sheetNames
End Sub

Explanation:

In the above code, we have a For Each loop that iterates over the worksheets inside the active workbook. Inside the loop, we are appending and storing the sheet names within the ‘sheetNames’ variable. Also, we have a ‘sheetCounter’ variable that gets incremented on each iteration.

After that, inside the loop, we also check if the value of the ‘sheetCounter’ variable has reached 3 (because we only want to display 3 sheet names).

If the ‘sheetCounter’ variable’s value has reached 3, we exit the loop using the ‘Exit For’ statement. Finally, we are displaying the value of the ‘sheetNames’ variable using a msgbox.

VBA Do While Loop

VBA Do While is another type of loop that repeatedly executes a set of statements while a condition continues to be True. The loop ends when the condition becomes false.

Syntax of Do While Loop In VBA

Do while loop has two syntaxes in VBA, these are as follows:

Syntax 1:

Do While condition
'Statements to be executed inside the loop
Loop

Or

Syntax 2:

Do
'Statements to be executed inside the loop
Loop While condition

In both the syntaxes, ‘condition’ is used as the loop backbone. On each iteration ‘While’ statement checks if the ‘condition’ evaluates to True or False. If the ‘condition’ is True, then the loop continues; otherwise, the loop terminates.

Before everything else, let’s try to understand the difference between these two syntaxes.

Difference Between the two Do While Syntaxes

As we can see in the first, do-while loop syntax, the ‘condition’ is checked as the first statement. This means if the condition is false, the do-while loop in syntax 1 will not perform any iterations.

Whereas in the second syntax, the ‘condition’ is checked as the last statement inside the loop. This means that even if the condition is false, the do-while loop in syntax 2 will perform at least 1 iteration. Only after that, the condition will be evaluated, and the next iteration will not happen.

So, syntax 2 guarantees to have at least 1 iteration irrespective of the condition being true or false.

Now, let’s try to understand how a do-while loop works.

How Does a Do While Loop Work

Syntax 1 –

Let’s say we have a Do While loop as follows:

Dim loop_ctr as Integer
loop_ctr = 1
Do While loop_ctr < 10
'Statements to be executed inside the loop
loop_ctr = loop_ctr + 1
Loop

• In the first two statements, the variable ‘loop_ctr’ is declared and initialized as 1.
• When the program control reaches the statement «Do While loop_ctr < 10», it checks if the value of the ‘loop_ctr’ is less than 10.
• If the ‘loop_ctr’ value is less than 10, the statements inside the body of the loop get executed sequentially, and finally, the ‘loop_ctr’ is incremented by 1.
• After this, the control again moves to the loop «Do While loop_ctr < 10», and the loop continues till the value of ‘loop_ctr’ becomes equal to 10.
• When the value of ‘loop_ctr’ becomes equal to 10, then the do while condition fails, and the control moves to the next statement after the do-while loop.

Syntax 2 –

Let’s say we have a Do While loop as follows:

Dim loop_ctr as Integer
loop_ctr = 1
Do
'Statements to be executed inside the loop</em>
loop_ctr = loop_ctr + 1
Loop While loop_ctr < 10

• In the first two statements, the variable ‘loop_ctr’ is declared and initialized as 1.
• When the program control reaches the «Do» statement, as there are no checks (like syntax 1), it just comes inside the loop and starts executing the statements inside the loop one by one and increments the ‘loop_ctr’ by 1.
• After executing the statements inside the loop body, it checks if the ‘loop_ctr’ is less than 10. If the ‘loop_ctr’ value is less than 10, another iteration starts.
• If the value of ‘loop_ctr’ becomes equal to 10, then the do while condition fails, and the control moves to the next statement after the do-while loop.

Note: In the second syntax, the Do-While Loop always iterates at-least-once since the condition to be checked is placed at the end of the loop.

Flow Diagram of a Do While Loop In VBA:

Let’s try to understand the control flow as depicted in the above flow chart:

Syntax 1 –

1. In this Do-While syntax, the loop condition is checked along with the Do statement.
2. If the condition is true, then the ‘code block’ inside the do-while loop is executed, and the next iteration begins. Each iteration before beginning checks the loop condition, and the ‘code block’ inside the do-while loop is only executed when the condition evaluates to true.
3. When the loop condition becomes false, then no more loop iterations occur, and the control flow jumps to the next statement outside the Do While loop.

Syntax 2 –

1. In this Do-While syntax, the loop condition is not checked along with the Do statement.
2. Since for the first iteration, no condition is checked. Hence the code block inside the do-while body gets executed.
3. After the first iteration, each subsequent iteration, before beginning, checks the loop condition, and the ‘code block’ inside the do-while loop is only executed when the condition evaluates to true.
4. When the loop condition becomes false, then no more loop iterations occur, and the control flow jumps to the next statement outside the Do While loop.

Few Simple Examples of Do While Loop In VBA

Example 1: Use VBA Do While Loop to print numbers from 1 to 10 in excel.

In this example, we have a range «A1:A10,» and we have to fill this range with numbers from 1-10. To do this we can use the below code:

Sub DoWhileLoopPrintNumbers()
Dim loop_ctr As Integer
loop_ctr = 1
Do While loop_ctr <= 10
ActiveSheet.Range("A1").Offset(loop_ctr - 1, 0).Value = loop_ctr
loop_ctr = loop_ctr + 1
Loop
MsgBox ("Loop Ends")
End Sub

Explanation:

In the above code, we have declared and initialized the ‘loop_ctr’ variable for our Do While loop. Next, along with the Do while statement, we have a condition to run the loop till the ‘loop_ctr’ value is less than or equal to 10.

Inside the Do While Loop body, we have written the code to write the ‘loop_ctr’ value on the excel sheet in the A column.

After this, there is a statement that increments the ‘loop_ctr’ for the next iteration.

Example 2: Use Do While Loop in VBA to find the sum of all the numbers between 1 to 20.

In this example, we will loop through all the numbers between 1 to 20 and sum them. Finally, we will be displaying the sum of the numbers from 1 to 20 on the screen.

To do this we can use the following code:

Sub WhileLoopSumNumbers()
Dim loop_ctr As Integer
Dim result As Integer
loop_ctr = 1
result = 0
Do While loop_ctr <= 20
result = result + loop_ctr
loop_ctr = loop_ctr + 1
Loop
MsgBox "Sum of numbers from 1-20 is : " & result
End Sub

Explanation:

In the above code, we have declared the loop counter ‘loop_ctr’ for our Do While loop. Next, we have declared another integer variable as ‘result’ for storing the sum of numbers from 1 to 20.

After this, along with the Do while statement, we have a condition to run the loop till the ‘loop_ctr’ value is less than or equal to 20.

Inside the Do While Loop body, we have added the value of ‘loop_ctr’ along with the result. This means that in the first iteration, the result’s value will be: 1, and in the second iteration, it will be : (1+2) = 3. Similarly, in the third iteration, the value will be: (3 + 3) = 6 and so on.

After this, there is a statement that increments the ‘loop_ctr’ for the next iteration.

The Do While loop in the above code iterates 20 times, sums all the numbers from 1 to 20, and finally displays the sum of these numbers in msgbox.

Example 3: Show the unique behavior of Do While Loop (In Syntax 2) to execute at-least-once even if the condition to be checked is False.

Sub DoWhileLoopTest()
Dim loop_ctr As Integer
loop_ctr = 100
Do
MsgBox "Loop Counter : " & loop_ctr
loop_ctr = loop_ctr + 1
Loop While loop_ctr <= 10
End Sub

Explanation:

In the above example, we have initialized the ‘loop_ctr’ as 100 and inside the loop condition we are checking ‘loop_ctr < 10’. This means the loop is only designed to iterate when the value of ‘loop_ctr’ is less than 10. But you will notice that despite the condition this do-while loop executes once.

The reason for this is: because according to syntax 2 of the Do While loop, there is no way to check conditions at the beginning of the loop. You can only check conditions at the end of the loop.

Note: We can fix this issue by simply using the Do While loop in Syntax 1 as shown:

Sub DoWhileLoopTest()
Dim loop_ctr As Integer
loop_ctr = 100
Do While loop_ctr <= 10
MsgBox "Loop Counter : " & loop_ctr
loop_ctr = loop_ctr + 1
Loop
End Sub

Writing a Nested Do While Loop

Similar to other loops, nesting is very much possible in Do While Loops. Let’s understand nested Do While loops this with an example.

Example 4: Print numbers from 1 to 10 in all the worksheets in an excel spreadsheet using a Do While Loop.

In this example, we need to print numbers from 1 to 10 in all the worksheets in an excel workbook using a do-while loop. To do this, we can make use of the following code:

Sub NestedDoWhileLoop()
Dim loop_ctr As Integer
Dim sheet As Integer
sheet = 1
Do While sheet <= Worksheets.Count
loop_ctr = 1
Do While loop_ctr <= 10
Worksheets(sheet).Range("A1").Offset(loop_ctr - 1, 0).Value = loop_ctr
loop_ctr = loop_ctr + 1
Loop
sheet = sheet + 1
Loop
MsgBox "Nested While Loop Completed!"
End Sub

Explanation:

In this example, there are two Do While Loops, one inside another. The Outer Do While Loop iterates over the variable ‘sheet’ and iterates till the value of the ‘sheet’ variable is less than or equal to ‘Worksheets.Count’ (i.e., the total count of worksheets in a workbook).

Inner Do While Loop iterates over the variable ‘loop_ctr’ and iterates till the value of ‘loop_ctr’ is less than or equal to 10. This helps us to print the numbers in a sequence.

Inside the body of the Inner Do While loop, we have a statement that prints the numbers between 1 to 10 in each worksheet (as per the outer loop).

The outer loop iterates over all the available worksheets sheets in the spreadsheet, whereas the inner loop iterates over the numbers from 1 to 10 for the current sheet.

This makes it possible to print numbers from 1 – 10 in all the available worksheets.

Infinite Loop Using a Do While Loop

Unlike a For Loop, a Do While Loop does not have a clear ‘start’, ‘end’ or ‘step_increments’, so it is very easy to make logical errors resulting in an infinite or an endless loop. Below is an example of a Do While endless loop:

'Do not run this code
Sub InfiniteDoWhileLoop()
Dim loop_ctr As Integer
loop_ctr = 1
Do While loop_ctr <= 10
ActiveSheet.Range("A1").Offset(loop_ctr - 1, 0).Value = loop_ctr
Loop
MsgBox ("Loop Ends")
End Sub

In the above code, we have simply missed the line to increment the loop counter i.e. ‘loop_ctr = loop_ctr + 1’ and this has made the loop infinite because the value of ‘loop_ctr’ will always be 1 (since it is never incremented) and hence the loop condition ‘While loop_ctr <= 10’ will always evaluate to true.

Tip: It is always a good idea to use a For Each or For Next loop over a Do While or Do Until loop (whenever possible).

How to Break Out or Exit of a Do While Loop

To break out of a Do While loop, we can use the ‘Exit Do’ statement. As soon as the VBA engine executes the ‘Exit Do’ statement, it exits the loop and takes the control to the next statement after the Do while loop.

Let’s see this with an example:

Example 5: Use a Do While loop in VBA to find the sum of the first 15 odd numbers between 1 to 100.

In this example, we have to find the first 15 odd numbers from 1 to 100 and then calculate their sum. Below is the code to do this:

Sub SumFirst15OddNumbers()
Dim loop_ctr As Integer
Dim odd_number_counter As Integer
Dim sum As Integer
loop_ctr = 1
Do While loop_ctr <= 100
If (loop_ctr Mod 2 <> 0) Then
sum = sum + loop_ctr
odd_number_counter = odd_number_counter + 1
End If
If (odd_number_counter = 15) Then
Exit Do
End If
loop_ctr = loop_ctr + 1
Loop
MsgBox "Sum of top 15 odd numbers is : " & sum
End Sub

Explanation:

In this example, we have three variables – ‘loop_ctr’, ‘odd_number_counter’, and ‘sum’. ‘loop_ctr’ is the loop counter variable, ‘odd_number_counter’ variable holds the count of odd numbers that have been summed and the ‘sum’ variable holds the sum of the first 15 odd numbers.

Inside the Do While loop, we loop through all the numbers from 1 to 100, one by one, and check if the number is odd. If the number is odd, we sum it and increment the ‘odd_number_counter’ by 1.

After the first IF block, another IF condition checks if the ‘odd_number_counter’ variable value is 15. If the value of ‘odd_number_counter’ is 15, then using the ‘Exit Do’ statement, we are breaking the loop as there is no point in continuing the loop further.

Finally, we are displaying the value of the ‘sum’ variable using a msgbox.

VBA Do Until Loop

Do Until loop is very similar to Do While loop; the only difference between them is that –

• A ‘do-while’ loop iterates as long as a certain condition is true.
• On the other hand, a ‘do-until’ loop iterates until a condition is no longer true.

Let’s try to understand this difference in simple terms:

For Instance: If we want to write a Do Loop that iterates from 1 to 10, with while keyword, the condition would be ‘Do While loop_ctr <= 10’ and with until keyword, the same condition can be written as ‘Do Until loop_ctr > 10’.

Which means:

• Until – repeat Until the count is greater than ten
• While – repeat While the count is less than or equal to ten

With these examples, you can clearly see – using Until and While is just the opposite way of writing the same condition.

Now, let’s have a look at the syntax of Do Until Loop.

Syntax of Do Until Loop In VBA

Similar to Do While loop, Do Until also has two syntaxes:

Syntax 1 –

Do Until condition
'Statements to be executed inside the loop
Loop

Or

Syntax 2 –

Do
'Statements to be executed inside the loop
Loop Until condition

Here, ‘condition’ is used as the loop backbone, the same as in the case of Do While Loop. On each iteration, Until statement checks, if the ‘condition’ evaluates to True or False. If the ‘condition’ is False, then the loop continues. Otherwise, the loop ends.

Now, let’s try to understand the difference between these two syntaxes.

Difference Between the two Do Until Syntaxes

As we can see in the first do until loop syntax, the ‘condition’ is checked as the first statement. This means if the condition is true, the do-until loop in syntax 1 will not perform any iterations.

Whereas in the second syntax, the ‘condition’ is checked as the last statement inside the loop. This means that even if the condition is true, the do-until loop in syntax 2 will perform at least 1 iteration. Only after that, the condition will be evaluated, and the next iteration will not happen.

So, syntax 2 guarantees to have at least 1 iteration irrespective of the condition being true or false.

How a Do Until Loop Works

Syntax 1 –

Let’s say we have a Do Until loop as follows:

Dim loop_ctr As Integer
loop_ctr = 1
Do Until loop_ctr > 10
'Statements to be executed inside the loop
loop_ctr = loop_ctr + 1
Loop

• In the first two statements, a variable ‘loop_ctr’ is declared and initialized as 1.
• When the program control reaches the statement «Do Until loop_ctr > 10», it checks if the value of the ‘loop_ctr’ is greater than 10.
• If the ‘loop_ctr’ value is less than or equal to 10, the statements inside the body of the loop get executed sequentially, and finally, the ‘loop_ctr’ is incremented by 1.
• After this, the control again moves to check the condition «Do Until loop_ctr > 10», and the loop continues till the value of ‘loop_ctr’ is less than or equal to 10.

Syntax 2 –

Dim loop_ctr As Integer
loop_ctr = 1
Do
'Statements to be executed inside the loop
loop_ctr = loop_ctr + 1
Loop Until loop_ctr > 10

• In the first two statements, a variable ‘loop_ctr’ is declared and initialized as 1.
• When the program control reaches the statement Do, it simply moves to the next statement as the Do statement doesn’t force the program to check any condition.
• After this, in the following statement, a variable ‘loop_ctr’ is incremented by 1.
• Next, ‘Loop Until loop_ctr > 10’ statement checks if the value of ‘loop_ctr’ is greater than 10 or not. If it is less than or equal to 10, then the program control again jumps to the Do statement, but if the value of ‘loop_ctr’ is greater than 10, it terminates the loop and the program control moves to the next statement.

Note: Syntax 2 of Do Until Loop always iterates at-least-once since the condition that is to be checked is placed at the end of the loop.

Flow Diagram of a Do Until Loop In VBA

Let’s try to understand the control flow as depicted in the above flow chart:

Syntax 1 –

1. In this Do-Until syntax, the loop condition is checked along with the Do statement.
2. If the condition is false, then the ‘code block’ inside the do-until loop is executed, and the next iteration begins. Each iteration before beginning checks the loop condition, and the ‘code block’ inside the do-until loop is only executed when the condition evaluates to false.
3. When the loop condition becomes true, then no more loop iterations occur, and the control flow jumps to the next statement outside the Do Until loop.

Syntax 2 –

1. In this Do-Until syntax, the loop condition is not checked along with the Do statement.
2. Since for the first iteration, no condition is checked. Hence the code block inside the do-until body gets executed.
3. After the first iteration, each subsequent iteration, before beginning, checks the loop condition, and the ‘code block’ inside the do-until loop is only executed when the condition evaluates to false.
4. When the loop condition becomes true, then no more loop iterations occur, and the control flow jumps to the next statement outside the Do Until loop.

Few Simple Examples of Do Until Loop In VBA

Example 1: Print numbers from 1 to 10 in excel using a VBA Do Until Loop.

In this example, we have a range «A1:A10,» and we have to fill this range with numbers from 1-10. To do this we can use the below code:

Sub DoUntilLoopPrintNumbers()
Dim loop_ctr As Integer
loop_ctr = 1
Do Until loop_ctr < 10
ActiveSheet.Range("A1").Offset(loop_ctr - 1, 0).Value = loop_ctr
loop_ctr = loop_ctr + 1
Loop
MsgBox ("Loop Ends")
End Sub

Explanation:

In the above code, first of all, we have declared and initialized the ‘loop_ctr’ variable for our Do Until loop. Next, along with the Do until statement, we have a condition to run the loop till ‘loop_ctr’ value is greater than 10.

Inside the Do Until Loop body, we have written the code to write the ‘loop_ctr’ value on the excel sheet in the A column.

After this, there is a statement that increments the ‘loop_ctr’ for the next iteration. As soon as the value of the ‘loop_ctr’ variable becomes greater than 10, the loop ends.

Example 2: Use Do Until Loop in VBA to find the sum of all the numbers between 1 to 20.

In this example, using a do until loop, we will iterate all the numbers between 1 to 20 and sum them. Finally, we will be displaying the sum of the numbers from 1 to 20 on the screen. To do this we can use the following code:

Sub DoUntilLoopSumNumbers()
Dim loop_ctr As Integer
Dim result As Integer
loop_ctr = 1
result = 0
Do Until loop_ctr > 20
result = result + loop_ctr
loop_ctr = loop_ctr + 1
Loop
MsgBox "Sum of numbers from 1-20 is : " & result
End Sub

Explanation:

In the above code, we have declared the loop counter ‘loop_ctr’ for our Do Until loop. Next, we have declared another integer variable as ‘result’ for storing the sum of numbers from 1 to 20.

After this, along with the Do Until statement, we have a condition to run the loop until the ‘loop_ctr’ becomes greater than 20.

Inside the Do Until Loop body, we have added the value of ‘loop_ctr’ along with the result. This means in the first iteration, the value of the result will be: 1, and in the second iteration, it will be : (1+2) = 3; similarly, in the third iteration, the value will be: (3 + 3) = 6 and so on.

After this, there is a statement that increments the ‘loop_ctr’ for the next iteration.

The Do Until loop in the above code iterates 20 times and sums all the numbers from 1 to 20, and finally displays the sum of these numbers in msgbox.

Example 3: Show the unique behavior of Do Until Loop (In Syntax 2) to execute at-least-once even if the condition to be checked is True.

Sub DoUntilLoopTest()
Dim loop_ctr As Integer
loop_ctr = 100
Do
MsgBox "Loop Counter : " & loop_ctr
loop_ctr = loop_ctr + 1
Loop Until loop_ctr > 10
End Sub

Explanation:

In the above example, we have initialized the ‘loop_ctr’ as 100 and inside the loop condition we are checking ‘loop_ctr > 10’. This means the loop is only designed to iterate when the value of ‘loop_ctr’ is less than 10. But you will notice that despite the condition this do-until loop executes once.

The reason for this is: because according to syntax 2 of the Do Until loop, there is no way to check conditions at the beginning of the loop. The condition can only be checked at the end of the loop.

Note: We can fix this issue by simply using the Do Until loop in Syntax 1 as shown:

Sub DoUntilLoopTest()
Dim loop_ctr As Integer
loop_ctr = 100
Do Until loop_ctr > 10
MsgBox "Loop Counter : " & loop_ctr
loop_ctr = loop_ctr + 1
Loop
End Sub

Writing a Nested Do Until Loop

Similar to other loops nesting is very much possible in Do Until Loop. Let’s see how to write a nested Do Until loop:

Example 4: Print numbers from 1 to 5 in all the worksheets in an excel spreadsheet using a Do Until Loop.

In this example, we need to print numbers from 1 to 5 in all the worksheets in an excel workbook using a do until loop. To do this, we can make use of the following code:

Sub NestedDoUntilLoop()
Dim loop_ctr As Integer
Dim sheet As Integer
sheet = 1
Do Until sheet > Worksheets.Count
loop_ctr = 1
Do Until loop_ctr > 5
Worksheets(sheet).Range("A1").Offset(loop_ctr - 1, 0).Value = loop_ctr
loop_ctr = loop_ctr + 1
Loop
sheet = sheet + 1
Loop
MsgBox "Nested Do Until Loop Completed!"
End Sub

Explanation:

In this example, there are two Do Until Loops, one inside another. The Outer Do Until Loop iterates over the variable ‘sheet’ and iterates until the value of the ‘sheet’ variable becomes greater than ‘Worksheets.Count’ (i.e., the total count of worksheets in a workbook).

Inner Do Until Loop iterates over the variable ‘loop_ctr’ and iterates until the value of ‘loop_ctr’ becomes greater than 5. This helps us to print the numbers in a sequence.

Inside the body of the Inner Do Until loop, we have a statement that prints the numbers between 1 to 5 in each worksheet (as per the outer loop).

The outer loop iterates over all the available worksheets in the spreadsheet, whereas the inner loop iterates over the numbers from 1 to 5 for the current sheet.

This makes it possible to print numbers from 1 – 5 in all the available worksheets.

Infinite Loop Using a Do Until Loop

Syntactically, Do Until Loop is very different from a For Loop since it does not provide a clear ‘start’, ‘end’ or ‘step_increments’, so it is very easy to make logical errors resulting in an infinite or an endless loop.

Below is an example of a Do Until endless loop:

'Do not run this code
Sub InfiniteDoUntilLoop()
Dim loop_ctr As Integer
loop_ctr = 1
Do Until loop_ctr > 10
ActiveSheet.Range("A1").Offset(loop_ctr - 1, 0).Value = loop_ctr
Loop
MsgBox ("Loop Ends")
End Sub

In the above code, we have simply missed the line to increment the loop counter i.e. ‘loop_ctr = loop_ctr + 1’ and this has made the loop infinite because the value of ‘loop_ctr’ will always be 1 (since it is never incremented) and hence the loop condition ‘Until loop_ctr > 10’ will always evaluate to false.

Tip: It is always a good idea to use a For Each or For Next loop over a Do While or Do Until loop (whenever possible).

How to Break Out or Exit of a Do Until Loop

Similar to a Do While Loop, a Do Until loop can also be exited using an ‘Exit Do’ statement. As soon as the VBA engine executes the ‘Exit Do’ statement, it exits the loop and takes control to the next statement after the Do Until loop.

Let’s see this with an example:

Example 5: Use a Do Until loop in VBA to find the sum of the first 20 even numbers between 1 to 100.

In this example, we must find the first 20 even numbers from 1 to 100 and then calculate their sum.

Below is the code to do this:

Sub SumFirst20EvenNumbers()
Dim loop_ctr As Integer
Dim even_number_counter As Integer
Dim sum As Integer
loop_ctr = 1
Do Until loop_ctr < 100
If (loop_ctr Mod 2 = 0) Then
sum = sum + loop_ctr
even_number_counter = even_number_counter + 1
End If
If (even_number_counter = 20) Then
Exit Do
End If
loop_ctr = loop_ctr + 1
Loop
MsgBox "Sum of top 20 even numbers is : " & sum
End Sub

Explanation:

In this example, we have three variables – ‘loop_ctr’, ‘even_number_counter’, and ‘sum’. ‘loop_ctr’ is the loop counter variable, ‘even_number_counter’ variable holds the count of even numbers that have been summed (because we only need to sum the first 20 even numbers) and ‘sum’ variable holds the sum of the first 20 even numbers.

Inside the Do Until loop, we loop through all the numbers from 1 to 100, one by one, and check if the number is even. If the number is even, we sum it and increment the ‘even_number_counter’ by 1.

After the first IF block, another IF condition checks if the ‘even_number_counter’ variable value is 20. If the value of ‘even_number_counter’ is 20, then using the ‘Exit Do’ statement, we break the loop as there is no point in running the loop further.

While Wend Loop In VBA (Obsolete)

While Wend loop was added in VBA just to make it backward compatible, Microsoft recommends using Do While Loop in place of While Wend Loop.

While Wend Loop is not as structured and flexible like a Do While Loop, it also doesn’t support the idea of prematurely exiting out of the loop.

Tip: If you are learning loops in VBA, then you can skip this topic. However, if you are dealing with a legacy code with While Wend statements, I would recommend you change them and start using the Do while loops instead.

Syntax of While Wend Loops

The syntax of While Wend Loop is as follows:

While condition
'Statements to be executed inside the loop
Wend

‘condition’ is used as the loop backbone. On each iteration, the While statement checks if the ‘condition’ evaluates to True or False. If the ‘condition’ is True, then the loop continues; otherwise, the loop terminates.

Example: Write a While Wend loop to print numbers from 1 to 10.

To do this, we can write the below code:

Sub WhileWendExample()
Dim loop_ctr As Integer
loop_ctr = 1
While loop_ctr <= 10
ActiveSheet.Range("A1").Offset(loop_ctr - 1, 0).Value = loop_ctr
loop_ctr = loop_ctr + 1
Wend
MsgBox "Loop Ends!"
End Sub

Explanation:

In the above code, first of all, we are declaring and initializing a loop counter variable ‘loop_ctr’ as 1. Next, there is a While statement along with the condition ‘While loop_ctr <= 10’.

This means that we need to iterate until the value of the ‘loop_ctr’ variable is less than or equal to 10. After this, we are printing the value of ‘loop_ctr’ in the active worksheet and then incrementing the loop counter. When the Wend statement is encountered, the next iteration starts.

The loop in the above example iterates 10 times, and after that, the value of ‘loop_ctr’ becomes 11, and hence the loop condition becomes false, and the control moves to the statement after the while when loop.

Finally, a message’ Loop Ends!’ is presented on the screen to notify the user that the loop has ended.

How To Write VBA Code In Excel

VBA code can be added to a spreadsheet using the Visual Basic Editor. To open the Visual Basic Editor in Excel, follow the below steps:

• If you are on Windows, press the keys (ALT + F11). If you are on MAC, press the keys (Opt + F11). This will open the Visual Basic Editor.

• After the Visual Basic Editor is opened. Go to «Insert» and click the «Module» option as shown in the image. This will insert a module object for your workbook.

• Now you can copy-paste the above codes in the module and run them using the execute button as shown.

Debugging Tips

• Use the F5 key to run the code.
• Use the F9 key to insert or remove a breakpoint.
• Use the F8 key to ‘step-into’ or run the code line by line. It can be used to debug the code and execute it line by line.

So, this was all about VBA Loops. Do let us know in case you have any queries related to the topic.