LmÉPï C Á npï À ÆµÀ ïì itech Analytic Solutions

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1 LmÉPï C Á npï À ÆµÀ ïì itech Analytic Solutions No. 9, 1st Floor, 8th Main, 9th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore itechanalytcisolutions@gmail.com Website: Mobile:

2 VBA Codes Loops (with example) No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 2

3 Excel VBA Loops, with examples. For Loop; Do While Loop; Do Until Loop. Loops are one of the most basic and powerful programming tools in VBA, and used across most programming languages. Loops are used to repeat a block of code as many times as required, until a given condition remains true or a specific point (or value) is reached, after which the the next section of code is executed. A loop enables you to write a few simple lines of code and achieve a far more significant output, just by repetition. There are three basic kinds of VBA Loops (subdivided into 6 loops as below): The For Loop The For Next Statements The For Each Next Statements The Do While Loop The Do While Loop Statements The Do Loop While Statements The Do Until Loop The Do Until Loop Statements The Do Loop Until Statements The For Loop The For Next Statements The For Next Loop repeats a block of code a specific number of times. For counter_variable = start_value To end_value [block of code] Next counter_variable This is explained with the help of a simple example: Sub fornext1() No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 3

4 Dim n As Integer Dim ntotal As Integer ntotal = 0 For n = 1 To 5 ntotal = n + ntotal Next n MsgBox ntotal The counter variable is "n", which is required to be declared. The start_value of the counter is 1, and its end_value is 5, both numeric values. Mentioning "Step" keyword is optional - this is a numeric value by which the counter is incremented each time the loop is run. The default step value is 1, unless specified. The Next statement increments the counter by the step value, and returns to the For statement, which repeats the block of code if the counter value does not exceed the "end" value of 5. If counter is equal to "end" value, the loop will continue; it stops when the "end" value is exceeded. The block of code which is repeated in this loop is: "ntotal = n + ntotal". Stepwise explanation: In this example, the counter increments by the default step value of 1, and in the first loop (where n = 1), ntotal adds up to 1 (adds 1 to its initial value of zero); The Next statement increments the counter by 1 (n = 2) and returns to For statement, and in the second loop ntotal adds up to 3 (adds 2 to its previous value of 1); The Next statement increments the counter by 1 (n = 3) and returns to For statement, and in the third loop ntotal adds up to 6 (adds 3 to its previous value of 3); The Next statement increments the counter by 1 (n = 4) and returns to For statement, and in the fourth loop ntotal adds up to 10 (adds 4 to its previous value of 6); The Next statement increments the counter by 1 (n = 5) and returns to For statement, and in the fifth loop ntotal adds up to 15 (adds 5 to its previous value of 10); No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 4

5 After executing the fifth loop, the Next statement increments the counter (ie. n) value to 6 and returns to the For statement, but this does not get executed because its value has gone beyond the "end" value of 5 specified here. MsgBox will display the value 15. In the above example, if the For statement is changed to "For n = 1 To 5 Step 2": The counter increments by the default step value of 2, and in the first loop (where n = 1), ntotal adds up to 1 (adds 1 to its initial value of zero); The Next statement increments the counter by 2 (n = 3) and returns to For statement, and in the second loop ntotal adds up to 4 (adds 3 to its previous value of 1); The Next statement increments the counter by 2 (n = 5) and returns to For statement, and in the third loop ntotal adds up to 9 (adds 5 to its previous value of 4); After executing the third loop, the Next statement increments the counter (ie. n) value to 7 and returns to the For statement, but this does not get executed because its value has gone beyond the "end" value of 5 specified here. MsgBox will display the value 9. Negative step values (count backword from a higher to a lower value): in the above example, the For statement is changed to "For n = 5 To 1 Step -1": In this example, the counter decrements by the step value of -1, and in the first loop (where n = 5), ntotal adds up to 5 (adds 5 to its initial value of zero); The Next statement decrements the counter by -1 (n = 4) and returns to For statement, and in the second loop ntotal adds up to 9 (adds 4 to its previous value of 5); The Next statement decrements the counter by -1 (n = 3) and returns to For statement, and in the third loop ntotal adds up to 12 (adds 3 to its previous value of 9); The Next statement decrements the counter by -1 (n = 2) and returns to For statement, and in the fourth loop ntotal adds up to 14 (adds 2 to its previous value of 12); The Next statement decrements the counter by -1 (n = 1) and returns to For statement, and in the fifth loop ntotal adds up to 15 (adds 1 to its previous value of 14); No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 5

6 After executing the fifth loop, the Next statement decrements the counter (ie. n) value to -1 and returns to the For statement, but this does not get executed because its value has gone beyond the "end" value of 1 specified here. MsgBox will display the value 15. The For Each Next Statements The For Each Next Loop repeats a block of code for each object in a group. It repeats execution of a block of code, for each element of a collection. The loop stops when all the elements in the collection have been covered, and execution moves to the section of code immediately following the Next statement. For Each object_variable In group_object_variable [block of code] Next object_variable Example: This loops through each worksheet in the workbook, and the code protects each with a password. Here, ws is the Worksheet Object variable, and the group or collection are all the Worksheets in this Workbook. Sub foreach1() Dim ws As Worksheet For Each ws In ThisWorkbook.Worksheets ws.protect Password:="123" Next ws No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 6

7 Example: This loops through each cell in the Range("A1:A10"), and the code sets background color of yellow in each. Here, icell is the Range Object variable, and the group or collection are all Cells in the Range("A1:A10"). Sub foreach2() Dim icell As Range For Each icell In ActiveSheet.Range("A1:A10") icell.interior.color = RGB(255, 255, 0) Next icell Nesting Loops: You can nest loops by putting one loop within another loop, upto unlimited number of times. The counter variable for each loop must be unique. You can nest one kind of loop within another different kind of loop. In a For Loop, it is necessary that the inner loop be completed before the Next statement of the outer loop is encountered. You can also nest one kind of control structure within another kind viz. you can nest an IF statement within a WITH block which can itself be nested within a For... Each Loop. However, control structures cannot be overlapped viz. each nested block has to close & terminate within its outer nested level. Example: Example of nesting an IF statement within a WITH block which is nested within a For... Each Loop. The code loops through each cell in the range A1:A10, and if cell value exceeds 5, the background color of that cell is set as Yellow, else Red for values of 5 and less. Sub nestingloops() Dim icell As Range For Each icell In ActiveSheet.Range("A1:A10") With icell No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 7

8 If icell > 5 Then.Interior.Color = RGB(255, 255, 0) Else.Interior.Color = RGB(255, 0, 0) End With Next icell The Exit For Statement You can exit the For Loop (both For... Next and For Each... Next Statements) early, without completing the full cycle, by using the Exit For statement. The Exit For statement will immediately stop execution of the existing loop and execute the section of code immediately following the Next statement, and in the case of inner nested level it will stop and execute the next outer nested level. You can have any number of Exit For statements in a loop. It is particularly useful in case you want to terminate the loop on reaching a certain value or satisfying a specific condition, or in case you want to terminate an endless loop at a certain point. Example: If Range ("A1") is blank, ntotal will add up to the value 55. If Range("A1") contains the value 5, the loop will terminate and exit when the counter (ie. n) reaches 5, and ntotal will add up to 15 (Note that the loop runs for the counter value of 5, and thereafter exits the loop). Sub exitfor1() Dim n As Integer Dim ntotal As Integer ntotal = 0 For n = 1 To 10 ntotal = n + ntotal If n = ActiveSheet.Range("A1") Then No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 8

9 Exit For Next n MsgBox ntotal The Do While Loop The Do While Loop Statements; The Do Loop While Statements The Do While Loop repeats a block of code indefinitely while the specified condition continues to be met and evaluated to True, and stops when the condition turns False. The condition can be tested either at the start or at the end of the Loop. "The Do While Loop Statements" test the condition at the start, while "The Do Loop While Statements" test the condition at the end of the Loop. If the condition is tested at the start of the Loop, the block of code does not execute if the condition is not met initially (and the loop does not run even once) whereas if the condition is tested at the end, the Loop runs atleast once. The Do While Loop Statements (The condition is tested at the start, in this Loop) Do While [Condition] [block of code] Loop The Do Loop While Statements (The condition is tested at the end, in this Loop) Do [block of code] Loop While [Condition] These two statements are explained with the help of examples. No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 9

10 Example 1: The condition (n>5) is tested at the start, and because it is not met, the loop does not execute even once. ntotal will return zero. Sub dowhile1() Dim n As Integer Dim ntotal As Integer n = 5 ntotal = 0 Do While n > 5 ntotal = n + ntotal n = n - 1 Loop MsgBox ntotal Example 2: The condition (n>5) is tested at the end, and because it is met, the loop executes but only once after which the value of n reduces to 4 and the Loop ends. ntotal returns the value 5. Sub dowhile2() Dim n As Integer Dim ntotal As Integer n = 5 ntotal = 0 Do No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 10

11 ntotal = n + ntotal n = n - 1 Loop While n > 5 MsgBox ntotal Example 3: Replace blank spaces with underscores in a Range of Cells, using VBA loops; or Remove blank spaces in a Range of Cells, using VBA loops. Sub dowhile3() 'Replace blank spaces with underscores in a Range of Cells, using VBA loops; or 'Remove blank spaces in a Range of Cells, using VBA loops. Dim icell As Range Dim textstring As String Dim n As Integer 'icell is a Cell in the specified Range which contains the textstring 'textstring is the text in a Cell in which blank spaces are to be replaced with underscores 'n is the position of blank space(s) occurring in a textstring For Each icell In ActiveSheet.Range("A1:A5") textstring = icell n = InStr(textString, " ") 'The VBA InStr function returns the position of the first occurrence of a string within another string. Using this to determine the position of the first blank space in the textstring. Do While n > 0 textstring = Left(textString, n - 1) & "_" & Right(textString, Len(textString) - n) 'blank space is replaced with the underscore character in the textstring No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 11

12 'textstring = Left(textString, n - 1) & Right(textString, Len(textString) - n) 'Use this line of code instead of the preceding line, to remove all blank spaces in the textstring n = InStr(textString, " ") Loop icell = textstring Next The Exit Do Statement You can exit the Do While Loop early, without completing the full cycle, by using the Exit Do statement. The Exit Do statement will immediately stop execution of the existing loop and execute the section of code immediately following the Loop statement, and in the case of inner nested level it will stop and execute the next outer nested level. You can have any number of Exit Do statements in a loop. It is particularly useful in case you want to terminate the loop on reaching a certain value or satisfying a specific condition, or in case you want to terminate an endless loop at a certain point. It is similar to the Exit For statement used to exit the For Loop. Example: If Range ("A1") is blank, ntotal will add up to the value 55. If Range("A1") contains the value 5, the loop will terminate and exit when the counter (ie. n) reaches 5, and ntotal will add up to 10 (Note that the loop does not run for the counter value of 5, and exits the loop on reaching this value). Sub exitdo1() Dim n As Integer Dim ntotal As Integer ntotal = 0 Do While n < 11 ntotal = n + ntotal No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 12

13 n = n + 1 If n = ActiveSheet.Range("A1") Then Exit Do Loop MsgBox ntotal The Do Until Loop The Do Until Loop Statements; The Do Loop Until Statements The Do Until Loop repeats a block of code indefinitely until the condition is met and evaluates to True. The condition can be tested either at the start or at the end of the Loop. "The Do Until Loop Statements" test the condition at the start, while "The Do Loop UntilStatements" test the condition at the end of the Loop. If the condition is tested at the start of the Loop, the block of code does not execute if the condition is met initially itself (and the loop does not run even once) whereas if the condition is tested at the end, the Loop runs atleast once. The Do Until Loop Statements (The condition is tested at the start, in this Loop) Do Until [Condition] [block of code] Loop The Do Loop Until Statements (The condition is tested at the end, in this Loop) Do [block of code] Loop Until [Condition] No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 13

14 These two statements are explained with the help of examples. Example 1: Sub dountil1() 'Colors the empty cells yellow, until a non-empty cell is encountered. If the first cell is not empty, the code will not execute because the condition of "Not Empty" is mentioned at the start of the loop. Dim rowno As Integer rowno = 1 Do Until Not IsEmpty(Cells(rowNo, 1)) Cells(rowNo, 1).Interior.Color = RGB(255, 255, 0) rowno = rowno + 1 Loop Example 2: Sub dountil2() 'Colors the empty cells yellow, until a non-empty cell is encountered. If the first cell is not empty, the code will still execute atleast once because the condition of "Not Empty" is mentioned at the end of the loop. Dim rowno As Integer rowno = 1 Do Cells(rowNo, 1).Interior.Color = RGB(255, 255, 0) rowno = rowno + 1 Loop Until Not IsEmpty(Cells(rowNo, 1)) No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 14

15 The Exit Do Statement You can exit the Do Until Loop early, without completing the full cycle, by using the Exit Do statement. It is similar to as in the Do WhileLoop, mentioned above. No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 15

16 More Examples of using VBA Loops: Image 1 Sub loopexample1() 'enter +ive and -ive numbers alternatively, in a column. Refer Image 1. Dim n As Integer For n = 1 To 10 Step 2 ActiveSheet.Cells(n, 1) = n * 2 Next n For n = 2 To 10 Step 2 ActiveSheet.Cells(n, 1) = n * -2 Next n No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 16

17 Image 2 Sub loopexample2() 'enter numbers in even rows only. Refer Image 2. Dim n As Integer n = 1 Do While n < 11 If n Mod 2 = 0 Then ActiveSheet.Cells(n, 1) = n * 3 n = n + 1 Loop No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 17

18 Image 3 Sub pyramidex1() 'Create a number pyramid with VBA loops. Refer Image 3. Dim irow As Integer, n As Integer, itext As String For irow = 1 To 5 'indicates number of rows For n = 1 To irow 'each row is having number of digits which equal to the row number itext = itext & irow Next n If irow < 5 Then 'to avoid creating line feed after the fifth row itext = itext & vbcrlf Next irow ActiveSheet.Range("A15") = itext 'MsgBox itext No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 18

19 Image 4 Sub pyramidex2() 'Create a number pyramid with VBA loops. Refer Image 4. Dim irow As Integer, n As Integer, itext As String irow = 5 'indicates number of rows For n = 1 To irow 'each row is having equal number of digits as the row number If n < irow Then 'to avoid creating line feed after the last row itext = itext & String(n, Format(n, "0")) & vbcrlf 'The VBA "String" function creates a string consisting of a single character repeated a specified number of times. Note that the VBA function of Format() returns a string/text value. Else itext = itext & String(n, Format(n, "0")) Next n ActiveSheet.Range("A17") = itext 'MsgBox itext No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 19

20 Image 5 Sub pyramidex3() 'Create a number pyramid with VBA loops. Refer Image 5. Dim irow As Integer, n As Integer, itext As String For irow = 1 To 5 For n = 1 To irow itext = itext & irow * 2-1 Next n If irow < 5 Then itext = itext & Chr(10) 'Chr(10) provides line feed/new line Next irow ActiveSheet.Range("A21") = itext 'MsgBox itext No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 20

21 Image 6 Sub pyramidex4() 'Create a number pyramid with VBA loops. Refer Image 6. Dim irow As Integer, n As Integer, itext As String For irow = 5 To 1 Step -1 For n = 1 To irow itext = itext & irow Next n If irow > 1 Then itext = itext & vbcrlf Next irow ActiveSheet.Range("A23") = itext 'MsgBox itext No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 21

22 Image 7 Sub pyramidex5() 'Create a number pyramid with VBA loops. Refer Image 7. Dim irow As Integer, n As Integer, m As Integer, itext As String For irow = 1 To 5 m = irow For n = 1 To irow itext = itext & m & " " m = m + 1 Next n If irow < 5 Then itext = itext & vbcrlf Next irow ActiveSheet.Range("A25") = itext 'MsgBox itext No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 22

23 Image 8 Sub pyramidex6() 'Create a number pyramid with VBA loops. Refer Image 8. Dim irow As Integer, n As Integer, m As Integer, itext As String m = 1 For irow = 1 To 4 For n = 1 To irow itext = itext & m & " " m = m + 1 Next n If irow < 4 Then itext = itext & vbcrlf Next irow ActiveSheet.Range("A27") = itext 'MsgBox itext No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 23

24 Image 9 Sub pyramidex7() 'Create a number pyramid with VBA loops. Refer Image 9. Dim irow As Integer, n As Integer, m As Integer, itext As String For irow = 1 To 5 m = irow For n = 1 To irow itext = itext & m & " " m = m + 2 Next n If irow < 5 Then itext = itext & vbcrlf Next irow ActiveSheet.Range("A29") = itext 'MsgBox itext No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 24

25 Image 10 Sub pyramidex8() 'Create a pyramid with VBA loops. Refer Image 10. Dim irow As Integer, n As Integer, itext As String irow = 5 For n = 1 To irow If n < irow Then 'to avoid creating line feed after the last row itext = itext & String(n, "#") & Chr(10) 'The VBA "String" function creates a string consisting of a single character repeated a specified number of times. Chr(10) provides line feed/new line. Else itext = itext & String(n, "#") Next ActiveSheet.Range("A31") = itext 'MsgBox itext No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 25

26 Image 11 Sub pyramidex9() 'Create a pyramid with VBA loops. Refer Image 11. Dim irow As Integer, n As Integer, itext As String irow = 5 For n = 1 To irow * 2 Step 2 irow = irow - 1 If n < 8 Then itext = itext & String(iRow, "-") & String(n, "*") & vbcrlf Else itext = itext & String(iRow, "-") & String(n, "*") Next ActiveSheet.Range("A33") = itext 'MsgBox itext No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 26

27 Sub palindromecheck1() 'Code to check if string is a Palindrome. A palindrome is a word, phrase, number, line or sequence that reads the same forward as it does backward. 'Note: Code does not differentiate upper and lower case, and does not ignore spacing. 'This code divides the text length by 2 and checks letters on each side with the other, to determine if text is Palindrome or not. Dim itext As String, n As Integer itext = "Racecar" itext = UCase(iText) 'remove this line to make the check case-sensitive For n = 1 To Len(iText) / 2 'divide text length by 2 to check letters on each side with the other If Mid(iText, n, 1) <> Mid(iText, Len(iText) - n + 1, 1) Then MsgBox "Not a Palindrome" Exit Sub Next n MsgBox "Palindrome" No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 27

28 Sub palindromecheck2() 'Code to check if string is a Palindrome. A palindrome is a word, phrase, number, line or sequence that reads the same forward as it does backward. 'Note: Code does not differentiate upper and lower case, and does not ignore spacing. 'This code builds the reverse text and checks the original and reverse texts, to determine if Palindrome or not. Dim itext As String, n As Integer itext = "Level" itext = LCase(iText) 'remove this line to make the check case-sensitive revtext = "" For n = Len(iText) To 1 Step -1 revtext = revtext & Mid(iText, n, 1) 'building the reverse text to compare with original text Next n If itext = revtext Then MsgBox "Palindrome" Else MsgBox "Not a Palindrome" No. 9, 1 st Floor, 8 th Main, 9 th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore Page: 28

LmÉPï C Á npï À ÆµÀ ïì itech Analytic Solutions

LmÉPï C Á npï À ÆµÀ ïì itech Analytic Solutions No. 9, 1st Floor, 8th Main, 9th Cross, SBM Colony, Brindavan Nagar, Mathikere, Bangalore 560 054 Email: itechanalytcisolutions@gmail.com Website: www.itechanalytcisolutions.com