Что являют собой циклы в Visual Basic? Кто является операторами цикла

Что являют собой циклы в Visual Basic? Кто является операторами цикла?

VB-циклы в Visual Basic for Application делают те же функции, что и в любом другом языке программирования. Цикл — это возможность повторять выполнение какой-нибудь части кода, пока не выполнится данное условие.

Если в остальных языках программирования с цикличностью незначительно трудно, потому что там быть может большая разновидность циклов, то в Visual Basic существует всего два вида схожих минискриптов:

  • циклы со счетчиком — подобные циклы производятся необходимое количество раз;
  • циклы с критериями — подобные минискрипты производятся до тех пор, пока не будет выполнено какое-либо обозначенное требование.

VB-циклы: циклы со счетчиком

  • «For. Next»;
  • «For. Each».

VB-цикл «For. Next»

Обычно в таковых минискриптах применяется переменная, которая может принять значения лишь из обозначенного спектра. И с каждым таковым значением переменной будет производиться действие, которое мы прописали конкретно в самом цикле.

К примеру:
For i = 0 To 9
Result = Result + iArrays(i)
Next i

В таком цикле у нас находится переменная «i», которая будет принимать величины от 0 и до 9. С каждой данной нам величиной будет проводиться операция из тела цикла. Непосредственно в нашем случае программка складывает элементы массива «iArrays» снутри переменной «Result».
В таком цикле по дефлоту шаг переменной равен будет «1», другими словами переменная будет брать величины 0, 1, 2, 3 и т. д. Но что если нас интересует иной шаг. Допустим, мы желаем, чтоб шаг был равен «0.5». Для этого варианта у нас есть главный термин «Step», который может найти шаг переменной.

К примеру:
For s = 0 To 9 Step 0.5
sResult = sResult + s
Next s

В этом случае наша переменная будет брать величины по последующему сценарию: 0, 0.5, 1, 1.5, 2, 2.5 и т. д. до 9.

Если задать главному термину «Step» отрицательное значение, тогда получим «оборотный отсчет», к примеру:
For s = 9 To 0 Step -1
sArray(s) = s
Next s

В этом случае переменная будет принимать значения по последующему принципу: 9, 8, 7, 6 и т. д. до 0.

Что являют собой циклы в Visual Basic?

VB-цикл «For. Each»

Оператор для остановки цикла «Exit For»

Данный оператор останавливает наш цикл. Опосля его объявления выполнение кода перебегает сходу к последующему опосля него оператору. Для что он нужен? Допустим, у нас есть некоторый большенный массив данных, который нам нужно перебрать в поисках подходящего значения. Для перебора массива мы создаем и запускаем цикл. Но кое-где к середине массива наш элемент найден. В таком случае для чего нам перебирать весь массив до конца, если мы можем в момент обнаружения подходящего нам значения массива оборвать программу и отдать возможность производиться последующим скриптам?

К примеру:
For x = 0 To 100000
If sValues(x) = sVal Then
IndexVal = x
Exit For
End If
Next x

Этот VB-цикл должен перебрать 100 000 значений массива и каждое значение должен будет ассоциировать с величиной переменной «sVal». Как будет найдено четкое совпадение, то наш минискрипт остановится.

VB-циклы: циклы с условием

  • «Do. While»;
  • «Do. Until».

VB-цикл «Do. While»

Данный минискрипт производится до того момента, пока может производиться обозначенное условие снутри цикла.

Обычный пример:
Dim x As Integer = 99
Do While x > 1
Console.WriteLine(x)
x -= 2
Loop

Другими словами этот наш минискрипт продолжит свою работу, пока величина нашей переменной «x» будет больше «1». При всем этом в таком цикле поначалу проверяется условие и лишь позже будет производиться скрипт снутри самого цикла.

VB-цикл «Do. Until»

Снова же, данный цикл незначительно похож на предшествующий: скрипт снутри самого цикла будет производиться до тех пор, пока обозначенное условие равно «True», другими словами способно производиться.

К примеру:
Dim x As Integer = 99
Do Until x

Заключение

VB-циклы достаточно обыкновенные, но при всем этом могут делать разные задачки, если в тело цикла заключить наиболее сложные условия, чем мы приводили в примерах. В любом случае циклы в Visual Basic призваны облегчить для вас работу, так что имеет смысл их лучше изучить и начать уже использовать.

Excel VBA Loops – For Each, For Next, Do While, Nested & More

To work effectively in VBA, you must understand Loops.

Loops allow you to repeat a code block a set number of times or repeat a code block on a each object in a set of objects.

First we will show you a few examples to show you what loops are capable of. Then we will teach you everything about loops.

VBA Loop Quick Examples

For Each Loops

For Each Loops loop through every object in a collection, such as every worksheet in workbook or every cell in a range.

Loop Through all Worksheets in Workbook

This code will loop through all worksheets in the workbook, unhiding each sheet:

Loop Through All Cells in Range

This code will loop through a range of cells, testing if the cell value is negative, positive, or zero:

Интересно почитать:  Программа для восстановления файлов эксель

vba else if statement

For Next Loops

Another type of “For” Loop is the For Next Loop. The For Next Loop allows you to loop through integers.

This code will loop through integers 1 through 10, displaying each with a message box:

Do While Loops

Do While Loops will loop while a condition is met. This code will also loop through integers 1 through 10, displaying each with a message box.

Do Until Loops

Conversely, Do Until Loops will loop until a condition is met. This code does the same thing as the previous two examples.

We will discuss this below, but you need to be extremely careful when creating Do While or Do Until loops so that you don’t create a never ending loop.

VBA Loop Builder

vba loop builder

This is a screenshot of the “Loop Builder” from our Premium VBA Add-in: AutoMacro. The Loop Builder allows you to quickly and easily build loops to loop through different objects, or numbers. You can perform actions on each object and/or select only objects that meet certain criteria.

The add-in also contains many other code builders, an extensive VBA code library, and an assortment of coding tools. It’s a must have for any VBA developer.

Now we will cover the different types of loops in depth.

VBA For Next Loop

For Loop Syntax

The For Next Loop allows you to repeat a block of code a specified number of times. The syntax is:

Where the items in brackets are optional.

  • [Dim Counter as Long] – Declares the counter variable. Required if Option Explicit is declared at the top of your module.
  • Counter – An integer variable used to count
  • Start – The start value (Ex. 1)
  • End – The end value (Ex. 10)
  • [Step Value] – Allows you to count every n integers instead of every 1 integer. You can also go in reverse with a negative value (ex. Step -1)
  • [Do Something] – The code that will repeat
  • Next [Counter] – Closing statement to the For Next Loop. You can include the Counter or not. However, I strongly recommend including the counter as it makes your code easier to read.

If that’s confusing, don’t worry. We will review some examples:

Count to 10

This code will count to 10 using a For-Next Loop:

For Loop Step

Count to 10 – Only Even Numbers

This code will count to 10 only counting even numbers:

Notice we added “Step 2”. This tells the For Loop to “step” through the counter by 2. We can also use a negative step value to step in reverse:

For Loop Step – Inverse

Countdown from 10

This code will countdown from 10:

Delete Rows if Cell is Blank

I’ve most frequently used a negative step For-Loop to loop through ranges of cells, deleting rows that meet certain criteria. If you loop from the top rows to the bottom rows, as you delete rows you will mess up your counter.

This example will delete rows with blank cells (starting from the bottom row):

Great Product. AutoMacro doesn’t just write your code, it teaches as you go!» — Tony, UK

Nested For Loop

You can “nest” one For Loop inside another For Loop. We will use Nested For Loops to create a multiplication table:

Exit For

The Exit For statement allows you to exit a For Next loop immediately.

You would usually use Exit For along with an If Statement, exiting the For Next Loop if a certain condition is met.

For example, you might use a For Loop to find a cell. Once that cell is found, you can exit the loop to speed up your code.

This code will loop through rows 1 to 1000, looking for “error” in column A. If it’s found, the code will select the cell, alert you to the found error, and exit the loop:

Important: In the case of Nested For Loops, Exit For only exits the current For Loop, not all active Loops.

Continue For

VBA does not have the “Continue” command that’s found in Visual Basic. Instead, you will need to use “Exit”.

VBA For Each Loop

The VBA For Each Loop will loop through all objects in a collection:

  • All cells in a range
  • All worksheets in a workbook
  • All shapes in a worksheet
  • All open workbooks

You can also use Nested For Each Loops to:

  • All cells in a range on all worksheets
  • All shapes on all worksheets
  • All sheets in all open workbooks
  • and so on…
  • Object – Variable representing a Range, Worksheet, Workbook, Shape, etc. (ex. rng)
  • Collection – Collection of objects (ex. Range(“a1:a10”)
  • [Do Something] – Code block to run on each object
  • Next [Object] – Closing statement. [Object] is optional, however strongly recommended.
Интересно почитать:  Vba excel сортировка диапазона

For Each Cell in Range

For Each Worksheet in Workbook

This code will loop through all worksheets in a workbook, unprotecting each sheet:

For Each Open Workbook

This code will save and close all open workbooks:

For Each Shape in Worksheet

This code will delete all shapes in the active sheet.

For Each Shape in Each Worksheet in Workbook

You can also nest For Each Loops. Here we will loop through all shapes in all worksheets in the active workbook:

For Each – IF Loop

As we’ve mentioned before, you can use an If statement within a loop, performing actions only if certain criteria is met.

This code will hide all blank rows in a range:

VBA Do While Loop

The VBA Do While and Do Until (see next section) are very similar. They will repeat a loop while (or until) a condition is met.

The Do While Loop will repeat a loop while a condition is met.

Here is the Do While Syntax:

  • Condition – The condition to test
  • [Do Something] – The code block to repeat

You can also set up a Do While loop with the Condition at the end of the loop:

We will demo each one and show how they differ:

Do While

Here is the Do While loop example we demonstrated previously:

Loop While

Now let’s run the same procedure, except we will move the condition to the end of the loop:

VBA Do Until Loop

Do Until Loops will repeat a loop until a certain condition is met. The syntax is essentially the same as the Do While loops:

and similarly the condition can go at the start or the end of the loop:

Do Until

This do Until loop will count to 10, like our previous examples

Loop Until

This Loop Until loop will count to 10:

Exit Do Loop

Similar to using Exit For to exit a For Loop, you use the Exit Do command to exit a Do Loop immediately

Here is an example of Exit Do:

End or Break Loop

As we mentioned above, you can use the Exit For or Exit Do to exit loops:

However, these commands must be added to your code before you run your loop.

If you are trying to “break” a loop that’s currently running, you can try pressing ESC or CTRL + Pause Break on the keyboard. However, this may not work. If it doesn’t work, you’ll need to wait for your loop to end or, in the case of an endless loop, use CTRL + ALT + Delete to force close Excel.

This is why I try to avoid Do loops, it’s easier to accidentally create an endless loop forcing you to restart Excel, potentially losing your work.

VBA Cells

By Pradeep SPradeep S

Excel VBA Cells

Excel VBA Cells Function

Cells are one type of element in excel VBA. (Three elements of excel is Workbooks, Worksheets and Ranges/Cells)

Hierarchical between these elements or object will be:

Valuation, Hadoop, Excel, Mobile Apps, Web Development & many more.

Basic Structure For Referring a Cell

Excel VBA allows you to refer to cells in many different ways, cells refers to single cells only. (Note: it can’t refer to multiple cells like Range (“A2:E7”)

It is used for referencing a cell object e.g. it can be written as Cells (6, 5) for referring a cell “F5” where 6 is the column number & 5 is the row number Cells takes row & column number as an argument, cells are located within the range object With the help of cells in VBA, we can perform three important tasks, i.e. we can

  1. Read content from a cell
  2. Write a value to a cell
  3. Change the format of a cell

Difference between range & cells in VBA is Cells usually refer to a single cell at a time, while Range references a group of cells. The cell is a property of range in excel sheet, which is a characteristic, where it is used to describe a range Cells only returns one cell which is used to represent cells within a range of the worksheet.

This cells property is used to specify a single cell or all cells on the worksheet, where it returns a single cell in the Cells collection.

Интересно почитать:  Изменить регистр в excel

Syntax of VBA Cells in Excel

The syntax for VBA cells function in excel is as follows:

Cells argument will consider two numeric arguments to represent row & column, where the first one is for representing row number & and the second or last one referring to as column number.

Row Index: Which is row number which we are referring to.

Column Index: Which is column number which we are referring to.

Note: Either numbers or letters can be used to specify the Column index in CELLS E.G. Cells (5, “E”)

Comma (,): Separator between them is the union operator, which is used to combine several range of cells.

Expression = Cells (4, 2) indicates it is “B4” Cell on an active worksheet in row 4 and col 2

Expression = Cells (4, “E”) indicates it is “B4” Cell on an active worksheet in row 4 and col 2

Above either of the code can be used to

Difference between Cell & Range syntax VBA code

To select cell B4 on the active worksheet, you can use either of the following examples:

How to Use VBA Cells in Excel?

We will learn how to use VBA cells function with a few examples in excel.

Example #1 – VBA Cells

Step 1: Select or click on Visual Basic in the Code group on the Developer tab or you can directly click on Alt + F11 shortcut key.

VBA Cells Developers

Step 2: To create a blank module, right-click on Microsoft excel objects, in that click on Insert and under the menu section select Module, where the blank module gets created.

VBA Cells Module 1

Step 3: Double click on it, it is also called a code window, where you need to type Sub Cells_Example1() as the first message without any quotes around it. Now, you can observe, Excel automatically adds the line End Sub below the first message line when you press Enter.

Code:

Step 4: Now, all the codes which you enter must be between these two lines, Now you can start typing CELLS VBA code or syntax. Before typing code, enter CTRL + SPACE where VBA Intellisense Drop-down Menu appears, which helps you out in writing the code & you can autocomplete words in the VB editor.

The dropdown contains a list of all the members of the VB OBJECT MODEL active reference (i.e. includes objects, properties, variables, methods, and constants). This feature helps out in saving time & prevent misspell the words or typo-error.

Step 5: After typing cells, click on the tab key to select it.

Code:

Step 6: Once you leave a space and enter open bracket “(”, CELLS argument will appear where it considers two numeric arguments to represent row & column index, where the first one is for representing row number & and the second or last one referring to as column number.

Code:

Step 7: Now, I enter the row index number as “4” & column index as “2” and close the bracket. Full stop and enter one space by clicking on the spacebar, now the cells argument is ready. And I want value in it. So, I enter again enter CTRL + SPACE where VBA Intellisense Drop-down Menu appears, type “Val” which means value.

Code:

Step 8: Suppose you want “HI” to appear in that cell. For that, you need to type = “HI”. and click enter.

Code:

Step 9: Now, the code is ready, you can run the macro by clicking the Run Sub button (i.e. green “play” button) or by pressing F5. You can observe “Hi” appears in the cell “B4”

Things to Remember

  • Only one cell can be referred at a time with the help of Cells property.
  • Cell property is very significant & useful in a programming loop.
  • If you missed out or don’t specify a worksheet (by its name in VBA code), Excel considers or assumes the ACTIVE Sheet in a workbook.
  • If you missed out or don’t specify row and column index argument, then Excel will refer to all cells on the worksheet. E.g. Cells is the syntax for all cells on the Active Sheet.
  • You can combine cells with range together to define a starting & ending pint of a range with variables.

Recommended Articles

This is a guide to VBA Cells. Here we discuss how to use Excel VBA Cells Function along with practical examples and downloadable excel template. You can also go through our other suggested articles –

Ссылка на основную публикацию
Adblock
detector