Byval vba excel описание

Excel VBA ByVal

In VBA, we have a statement called ByVal which is used for calling the value from the subprocedure when the main procedure value is down to 0 or in other words when the value is reset. Where ByVal stands for By Value, which means replacing the main value by the value of another subprocedure. Excel VBA ByVal is the reference of linking once sub procedure with others so that we can use the linked sub procedure’s value by calling it using By Val. We can also give the reference of the value using ByRef. ByVal is used when we want to call a value from another sub procedure, but we do not want to change the value of argument whereas ByRef is used when we want to change the value using subprocedure.

VBA ByVal does not have any specific syntax which we need to follow. But the correct position of ByVal in VBA code will definitely make complete sense out of it. The above explanation would be much clear using the example shown below.

How to Use ByVal Statement in VBA Excel?

We will learn how to use a ByVal Statement in Excel by using the VBA Code.

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

Example #1

To know the values from other subprocedures, when the main procedure value is down to 0 or in other words when the value is reset. For this, follow the below steps:

Step 1: Insert a new module inside Visual Basic Editor (VBE). Click on Insert tab > select Module.

Step 2: Write the subprocedure in the name of the performed operations or any name.

Code:

Sub VBA_ByVal()

End Sub

Step 3: Define a variable as Integer using DIM as shown below.

Code:

Sub VBA_ByVal()

Dim A As Integer

End Sub

Step 4: Assign a number to defined variable A. We are choosing number 10.

Code:

Sub VBA_ByVal()

Dim A As Integer
A = 10

End Sub

Step 5: Use the message box to see the value stored in variable A.

Code:

Sub VBA_ByVal()

Dim A As Integer
A = 10
MsgBox A

End Sub

Step 6: Now after that, we will be writing another sub procedure, by that we will be calling another value for the same variable.

Code:

Sub VBA_ByVal()

Dim A As Integer
A = 10
MsgBox A

End Sub

Sub Val_Section(ByVal A As Integer)

End Sub

Step 7: Then we will use the same variable A and add any number to see the change in value from the main procedure.

Code:

Sub VBA_ByVal()

Dim A As Integer
A = 10
MsgBox A

End Sub

Sub Val_Section(ByVal A As Integer)

A = A + 12

End Sub

Step 8: Now we will compile the code by pressing the F8 function key. We will see, as the compiler reaches the variable A, hovering the cursor there will reflect the value as 0 which is the initial value.

Step 9: And once the cursor reaches at message box, then the value will be changed to 10 as now code has compiled till that.

Step 10: Now run the code by pressing function key F5 and to run the code, click on the Play button located below the menu bar, the message box will give us the value as 10.

Step 11: Now to call the value from below written sub procedure to the main procedure, use Val_Section which is our 2^nd subprocedure name with variable A.

Code:

Sub VBA_ByVal()

Dim A As Integer
A = 10
MsgBox A
Val_Section A

End Sub

Sub Val_Section(ByVal A As Integer)

A = A + 12

End Sub

Step 12: Now if again compile the code using the F8 key and we will notice once the compiler reaches End Sub of 2^nd sub procedure, on hovering the cursor there we will see the variable A has now the summed value as 22 adding the number from both the subprocedures.

Example #2

There is another method to call the value from other sub procedure to the main procedure. For this, follow the below steps:

Step 1: For this, we will be using the same first half of the code as shown below.

Code:

Sub VBA_Byval2()

Dim A As Integer
A = 10
MsgBox A

End Sub

Step 2: Now continuing the code, start the subprocedure for ByVal again as Integer.

Code:

Sub VBA_Byval2()

Dim A As Integer
A = 10
MsgBox A

End Sub

Sub Val_Section(ByVal A As Integer)

End Sub

Step 3: Here we will choose a different value which we want to call in the same variable A as 15.

Code:

Sub VBA_Byval2()

Dim A As Integer
A = 10
MsgBox A

End Sub

Sub Val_Section(ByVal A As Integer)

A = 15

End Sub

Step 4: Now to call the value mentioned in 2^nd sub procedure, we will use word CALL with the name of 2^nd sub procedure with variable A as shown below in the first part of the code.

Code:

Sub VBA_Byval2()

Dim A As Integer
A = 10
MsgBox A
Call Val_Section(A)

End Sub

Sub Val_Section(ByVal A As Integer)

A = 15

End Sub

Step 5: Similar to the procedure shown in example-1, compile the code using F8 step by step. We will see, as the compiler compiles the first subprocedure, we will get the message box with number 10 which we have used in variable A.

Continuing the compiling, as we reach at value 15 of variable A from the 2^nd sub procedure, then hovering the cursor will reflect the value as 10 which is the same as 1^st subprocedure.

And at last when our compiler reaches at End Sub then it will reflect the value as 15 after hovering the cursor, which is now called by using ByVal operation in the first subprocedure. But the message will only reflect the value as 10.

Pros & Cons of VBA ByVal

Below are the pros and cons of VBA ByVal:

• It is very easy to implement the ByVal even using the simple code of storing any number.
• We can pass any number as per the data type used with the limit range.
• VBA ByVal doesn’t reflect the updated or called value from the other sub procedure through the message box. It carries the same value even the message box pops up multiple times.

Things to Remember

• VBA ByVal and ByRef both are used for giving the reference. But the ByRef is only used for giving the reference whereas ByVal is used for calling the values stored in a different subprocedure.
• Hover the cursor at the variable name only to see the current position of value. Even after the compiler passes from there, the updated value will be seen only by hovering the cursor at the exact position.
• VBA ByVal carries the same value there in the first subprocedure once the code is run. And whatever changes happen when we call the value using ByVal, it will again reset to the previous value only.
• Once we are done with writing the code, always remember to save the code in Macro enabled excel format which is used for saving VBA Code.

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

1. How to Use VBA Login?
2. VBA Month | Examples With Excel Template
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Excel VBA ByVal Function Argument

ByVal is a statement in VBA. ByVal stands for “By Value,” i.e., when the subprocedure calls in from the procedure, the value of the variables is reset to the new value from the new procedure called in.

In VBA, when we work with functions that call in different functions, there are certain circumstances that the value for the original argument is changed when calls the function. The ByVal statement prohibits the procedure or the code from changing the value for the argument.

By reading the explanation, we know it is not easy to understand. But with practical examples of function, we can understand it better.

How to use ByVal Argument in VBA?

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

Example #1

Look at the VBA codesVBA code refers to a set of instructions written by the user in the Visual Basic Applications programming language on a Visual Basic Editor (VBE) to perform a specific task.read more below.

Code:

Sub Macro1()

    Dim k As Integer

    k = 50

    Macro2 k

    MsgBox k

End Sub

Sub Macro2(ByVal k As Integer)

    k = k + 5

End Sub

The above two macro procedures have a common variable, “k,” across procedures. Let me explain this in detail before we see the result.

In the first Macro, we have assigned the value of 50 to the variable “k.”

Dim k As Integer

k = 50

Next, we have called the second macro procedure from the first Macro.

Macro2 k

In Macro2, we have reset the variable’s value to k = k + 5. In this macro, we have used the ByVal argument to assign the value to the variable “k.”

Now, to understand “ByVal,” let’s run the VBA code by pressing the F8 key.

#1 – Upon pressing the F8 key first, it will highlight the first line of the Macro1.

At this point, place a cursor on the variable “k.” It should show the value of the variable “k.”

At the moment, the value of “k” is zero.

#2 – Press the F8 key again, and it will jump to the third line.

Even now, the value of “k” is still zero.

#3 – Press the F8 key now. See the value of the k.

Since the “k” value sets to 50 and the code executes, the value shows as 50.

#4 – The highlighted line is “Macro2 k,” i.e., pressing the F8 key will jump to the second procedure, Macro2.

#5 – Even now, the value of variable “k” in this procedure also shows as 50. But inside this macro, we are resetting the value of the variable “k” as k = k + 5, i.e., 55. So, now press the F8 key two more times.

As you can see above, the “k” value is 55 now.

#6 – Press the F8 key. It will jump back to the Macro1 procedure.

When the macro jumps back to the original procedure Macro1, our variable “k” value is no longer 55 but rather the original value in this procedure, i.e., 50.

When you press the F8 key, we can see only 50 in the message box in VBAVBA MsgBox function is an output function which displays the generalized message provided by the developer. This statement has no arguments and the personalized messages in this function are written under the double quotes while for the values the variable reference is provided.read more.

As we have told at the beginning of the article “ByVal,” the argument does not carry values from one procedure to another even though it carries the variable’s value from the first macro to the second by the moment. It encounters the line “ByVal” when it returns to the original macro. It resets the value to the original value in the procedure only.

Example #2

Now, take a look at the below two macros.

Code:

Sub P1()

    Dim k As Integer: k = 10

    Call P2(k)

    MsgBox k

End Sub

Sub P2(ByVal k As Integer)

     k = 15

End Sub

• It is similar to the first example. In the macro “P1,” we have assigned the value of 10 to the variable “k,” and in the same macro “P1,” we have called the second macro “P2” with variable “k.”
• In the second macro, “P2,” we have used the ByVal argument. This time, the value of variable “k” is 15.

This macro carries the value of variable “k” as ten from macro “P1” to macro “P2.” So, this macro will reset the value to 15, but the moment it comes back to finish the macro to the first macro, “P1,” the value of “k” back to 10, not 15.

Things to Remember

The ByVal argument does not affect the variable value even after running the macro. Still, we can carry the variable’s value from one macro to the other with the By Ref argument.

Recommended Articles

This article has been a guide to VBA Byval. Here, we discuss using the ByVal argument in VBA along with the examples and downloadable Excel template. You can learn more about VBA from the following articles: –

• VBA ByRef Argument Type Mismatch
• VBA Split String into Array
• Set Range in VBA
• VBA Examples

Function statement

Declares the name, arguments, and code that form the body of a Function procedure.

Syntax

[Public | Private | Friend] [ Static ] Function name [ ( arglist ) ] [ As type ]
[ statements ]
[ name = expression ]
[ Exit Function ]
[ statements ]
[ name = expression ]
End Function

The Function statement syntax has these parts:

Part	Description
Public	Optional. Indicates that the Function procedure is accessible to all other procedures in all modules. If used in a module that contains an Option Private, the procedure is not available outside the project.
Private	Optional. Indicates that the Function procedure is accessible only to other procedures in the module where it is declared.
Friend	Optional. Used only in a class module. Indicates that the Function procedure is visible throughout the project, but not visible to a controller of an instance of an object.
Static	Optional. Indicates that the Function procedure’s local variables are preserved between calls. The Static attribute doesn’t affect variables that are declared outside the Function, even if they are used in the procedure.
name	Required. Name of the Function; follows standard variable naming conventions.
arglist	Optional. List of variables representing arguments that are passed to the Function procedure when it is called. Multiple variables are separated by commas.
type	Optional. Data type of the value returned by the Function procedure; may be Byte, Boolean, Integer, Long, Currency, Single, Double, Decimal (not currently supported), Date, String (except fixed length), Object, Variant, or any user-defined type.
statements	Optional. Any group of statements to be executed within the Function procedure.
expression	Optional. Return value of the Function.

The arglist argument has the following syntax and parts:

[ Optional ] [ ByVal | ByRef ] [ ParamArray ] varname [ ( ) ] [ As type ] [ = defaultvalue ]

Part	Description
Optional	Optional. Indicates that an argument is not required. If used, all subsequent arguments in arglist must also be optional and declared by using the Optional keyword. Optional can’t be used for any argument if ParamArray is used.
ByVal	Optional. Indicates that the argument is passed by value.
ByRef	Optional. Indicates that the argument is passed by reference. ByRef is the default in Visual Basic.
ParamArray	Optional. Used only as the last argument in arglist to indicate that the final argument is an Optional array of Variant elements. The ParamArray keyword allows you to provide an arbitrary number of arguments. It may not be used with ByVal, ByRef, or Optional.
varname	Required. Name of the variable representing the argument; follows standard variable naming conventions.
type	Optional. Data type of the argument passed to the procedure; may be Byte, Boolean, Integer, Long, Currency, Single, Double, Decimal (not currently supported) Date, String (variable length only), Object, Variant, or a specific object type. If the parameter is not Optional, a user-defined type may also be specified.
defaultvalue	Optional. Any constant or constant expression. Valid for Optional parameters only. If the type is an Object, an explicit default value can only be Nothing.

If not explicitly specified by using Public, Private, or Friend, Function procedures are public by default.

If Static isn’t used, the value of local variables is not preserved between calls.

The Friend keyword can only be used in class modules. However, Friend procedures can be accessed by procedures in any module of a project. A Friend procedure does not appear in the type library of its parent class, nor can a Friend procedure be late bound.

Function procedures can be recursive; that is, they can call themselves to perform a given task. However, recursion can lead to stack overflow. The Static keyword usually isn’t used with recursive Function procedures.

All executable code must be in procedures. You can’t define a Function procedure inside another Function, Sub, or Property procedure.

The Exit Function statement causes an immediate exit from a Function procedure. Program execution continues with the statement following the statement that called the Function procedure. Any number of Exit Function statements can appear anywhere in a Function procedure.

Like a Sub procedure, a Function procedure is a separate procedure that can take arguments, perform a series of statements, and change the values of its arguments. However, unlike a Sub procedure, you can use a Function procedure on the right side of an expression in the same way you use any intrinsic function, such as Sqr, Cos, or Chr, when you want to use the value returned by the function.

You call a Function procedure by using the function name, followed by the argument list in parentheses, in an expression. See the Call statement for specific information about how to call Function procedures.

To return a value from a function, assign the value to the function name. Any number of such assignments can appear anywhere within the procedure. If no value is assigned to name, the procedure returns a default value: a numeric function returns 0, a string function returns a zero-length string («»), and a Variant function returns Empty. A function that returns an object reference returns Nothing if no object reference is assigned to name (using Set) within the Function.

The following example shows how to assign a return value to a function. In this case, False is assigned to the name to indicate that some value was not found.

Variables used in Function procedures fall into two categories: those that are explicitly declared within the procedure and those that are not.

Variables that are explicitly declared in a procedure (using Dim or the equivalent) are always local to the procedure. Variables that are used but not explicitly declared in a procedure are also local unless they are explicitly declared at some higher level outside the procedure.

A procedure can use a variable that is not explicitly declared in the procedure, but a naming conflict can occur if anything you defined at the module level has the same name. If your procedure refers to an undeclared variable that has the same name as another procedure, constant, or variable, it is assumed that your procedure refers to that module-level name. Explicitly declare variables to avoid this kind of conflict. Use an Option Explicit statement to force explicit declaration of variables.

Visual Basic may rearrange arithmetic expressions to increase internal efficiency. Avoid using a Function procedure in an arithmetic expression when the function changes the value of variables in the same expression. For more information about arithmetic operators, see Operators.

Example

This example uses the Function statement to declare the name, arguments, and code that form the body of a Function procedure. The last example uses hard-typed, initialized Optional arguments.

Using the ParamArray keyword enables a function to accept a variable number of arguments. In the following definition, it is passed by value.

Optional arguments can have default values and types other than Variant.

See also

Support and feedback

Have questions or feedback about Office VBA or this documentation? Please see Office VBA support and feedback for guidance about the ways you can receive support and provide feedback.

Источник

VBA-Урок 9. Процедуры и функции

Public — Private

На данный момент, все процедуры, мы создавали, имеют тип Public , что означает, что они доступны из любого модуля.

Чтобы сделать процедуру доступной только в определенном модуле, используется ключевое слово Private:

Запуск процедуры с середины другой процедуры

Чтобы выполнить процедуру с середины другой процедуры, просто введите ее название.

Здесь есть очень простой пример:

Аргументы

Аргументы делают возможным использование значений из процедуры в под-процедуры (запомните, что по умолчанию, переменные являются доступны только по той процедуры, в которой они были объявлены).

К процедуре «warning» был добавлен аргумент, в данном случае это переменная «var_text» с типом «String» (строка):

Эта процедура требует аргумент, поэтому мы должны поставить значение после «warning», чтобы выполнить ее:

Когда мы хотим прописать несколько аргументов, тогда они должны быть отделены запятыми.

Необязательные аргументы

По умолчанию, если процедура имеет аргументы, то они должны быть обязательно проставлены, и если они не проставлены, тогда процедура не выполнится.

Необязательный аргумент может быть добавлен после обязательного, с помощью ключевого слова Optional . Например:

Теперь эта процедура может быть выполнена с или без опционального аргумента, как здесь:

Аргументы должны быть введены в правильном порядке.

Чтобы протестировать, присутствует ли опциональный аргумент в процедуре, мы используем функцию IsMissing . Эта функция совместима только с некоторыми типами функций (типа Variant) и это является решающим, так как тип необязательно аргументов не был указан в объявлении (необъявленный тип = Variant).

Здесь есть пример, который использует два фрагмента кода, которые рассматривались выше:

См. рисунок ниже (пример 1):

ByRef — ByVal

По умолчанию, аргументы имеют тип ByRef , что означает: если переменная передается как аргумент, ссылка на нее будет также передаваться. Иными словами, если переменная была изменена другой под-процедурой, то она также будет изменена во внешней процедуре, которая вызывает эту под-процедуру.

Чтобы стало понятнее, ниже есть пример того, что произойдет, если макрос будет запущен на выполнение:

Второй метод заключается в использовании ByVal .

В отличие от ByRef , который передает ссылки (ярлык), ByVal передает значение, которое означает, что значение передано как аргумент не было изменено.

Ниже вы можете увидеть как предыдущий код и ByVal работают:

Что вам нужно запомнить: используйте ByVal когда переменная не должна быть изменена .

Функции

Основным отличием между процедурой и функцией является то, что функция возвращает значение.

Вот простой пример:

Функция может быть использована на рабочем листе, подобно любой другой функции в Excel.

Например, чтобы получить квадрат значения, которое введенное в ячейку A1:

Источник

Sub statement

Declares the name, arguments, and code that form the body of a Sub procedure.

Syntax

[ Private | Public | Friend ] [ Static ] Sub name [ ( arglist ) ]
[ statements ]
[ Exit Sub ]
[ statements ]
End Sub

The Sub statement syntax has these parts:

Part	Description
Public	Optional. Indicates that the Sub procedure is accessible to all other procedures in all modules. If used in a module that contains an Option Private statement, the procedure is not available outside the project.
Private	Optional. Indicates that the Sub procedure is accessible only to other procedures in the module where it is declared.
Friend	Optional. Used only in a class module. Indicates that the Sub procedure is visible throughout the project, but not visible to a controller of an instance of an object.
Static	Optional. Indicates that the Sub procedure’s local variables are preserved between calls. The Static attribute doesn’t affect variables that are declared outside the Sub, even if they are used in the procedure.
name	Required. Name of the Sub; follows standard variable naming conventions.
arglist	Optional. List of variables representing arguments that are passed to the Sub procedure when it is called. Multiple variables are separated by commas.
statements	Optional. Any group of statements to be executed within the Sub procedure.

The arglist argument has the following syntax and parts:

[ Optional ] [ ByVal | ByRef ] [ ParamArray ] varname [ ( ) ] [ As type ] [ = defaultvalue ]

Part	Description
Optional	Optional. Keyword indicating that an argument is not required. If used, all subsequent arguments in arglist must also be optional and declared by using the Optional keyword. Optional can’t be used for any argument if ParamArray is used.
ByVal	Optional. Indicates that the argument is passed by value.
ByRef	Optional. Indicates that the argument is passed by reference. ByRef is the default in Visual Basic.
ParamArray	Optional. Used only as the last argument in arglist to indicate that the final argument is an Optional array of Variant elements. The ParamArray keyword allows you to provide an arbitrary number of arguments. ParamArray can’t be used with ByVal, ByRef, or Optional.
varname	Required. Name of the variable representing the argument; follows standard variable naming conventions.
type	Optional. Data type of the argument passed to the procedure; may be Byte, Boolean, Integer, Long, Currency, Single, Double, Decimal (not currently supported), Date, String (variable-length only), Object, Variant, or a specific object type. If the parameter is not Optional, a user-defined type may also be specified.
defaultvalue	Optional. Any constant or constant expression. Valid for Optional parameters only. If the type is an Object, an explicit default value can only be Nothing.

If not explicitly specified by using Public, Private, or Friend, Sub procedures are public by default.

If Static isn’t used, the value of local variables is not preserved between calls.

The Friend keyword can only be used in class modules. However, Friend procedures can be accessed by procedures in any module of a project. A Friend procedure doesn’t appear in the type library of its parent class, nor can a Friend procedure be late bound.

Sub procedures can be recursive; that is, they can call themselves to perform a given task. However, recursion can lead to stack overflow. The Static keyword usually is not used with recursive Sub procedures.

All executable code must be in procedures. You can’t define a Sub procedure inside another Sub, Function, or Property procedure.

The Exit Sub keywords cause an immediate exit from a Sub procedure. Program execution continues with the statement following the statement that called the Sub procedure. Any number of Exit Sub statements can appear anywhere in a Sub procedure.

Like a Function procedure, a Sub procedure is a separate procedure that can take arguments, perform a series of statements, and change the value of its arguments. However, unlike a Function procedure, which returns a value, a Sub procedure can’t be used in an expression.

You call a Sub procedure by using the procedure name followed by the argument list. See the Call statement for specific information about how to call Sub procedures.

Variables used in Sub procedures fall into two categories: those that are explicitly declared within the procedure and those that are not. Variables that are explicitly declared in a procedure (using Dim or the equivalent) are always local to the procedure. Variables that are used but not explicitly declared in a procedure are also local unless they are explicitly declared at some higher level outside the procedure.

A procedure can use a variable that is not explicitly declared in the procedure, but a naming conflict can occur if anything you defined at the module level has the same name. If your procedure refers to an undeclared variable that has the same name as another procedure, constant or variable, it is assumed that your procedure is referring to that module-level name. To avoid this kind of conflict, explicitly declare variables. Use an Option Explicit statement to force explicit declaration of variables.

You can’t use GoSub, GoTo, or Return to enter or exit a Sub procedure.

Example

This example uses the Sub statement to define the name, arguments, and code that form the body of a Sub procedure.

See also

Support and feedback

Have questions or feedback about Office VBA or this documentation? Please see Office VBA support and feedback for guidance about the ways you can receive support and provide feedback.

Источник