Excel vba function calls

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

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Call statement

Transfers control to a Sub procedure, Function procedure, or dynamic-link library (DLL) procedure.

Syntax

[ Call ] name [ argumentlist ]

The Call statement syntax has these parts:

Part	Description
Call	Optional; keyword. If specified, you must enclose argumentlist in parentheses. For example: Call MyProc(0)
name	Required. Name of the procedure to call.
argumentlist	Optional. Comma-delimited list of variables, arrays, or expressions to pass to the procedure. Components of argumentlist may include the keywords ByVal or ByRef to describe how the arguments are treated by the called procedure. However, ByVal and ByRef can be used with Call only when calling a DLL procedure. On the Macintosh, ByVal and ByRef can be used with Call when making a call to a Macintosh code resource.

You are not required to use the Call keyword when calling a procedure. However, if you use the Call keyword to call a procedure that requires arguments, argumentlist must be enclosed in parentheses. If you omit the Call keyword, you also must omit the parentheses around argumentlist. If you use either Call syntax to call any intrinsic or user-defined function, the function’s return value is discarded.

To pass a whole array to a procedure, use the array name followed by empty parentheses.

Example

This example illustrates how the Call statement is used to transfer control to a Sub procedure, an intrinsic function, and a dynamic-link library (DLL) procedure. DLLs are not used on the Macintosh.

See also

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VBA Function – Call, Return Value, & Parameters

In this Article

This tutorial will teach you to create and use functions with and without parameters in VBA

VBA contains a large amount of built-in functions for you to use, but you are also able to write your own. When you write code in VBA, you can write it in a Sub Procedure, or a Function Procedure. A Function Procedure is able to return a value to your code. This is extremely useful if you want VBA to perform a task to return a result. VBA functions can also be called from inside Excel, just like Excel’s built-in Excel functions.

Creating a Function without Arguments

To create a function you need to define the function by giving the function a name. The function can then be defined as a data type indicating the type of data you want the function to return.

You may want to create a function that returns a static value each time it is called – a bit like a constant.

If you were to run the function, the function would always return the value of 50.

You can also create functions that refer to objects in VBA but you need to use the Set Keyword to return the value from the function.

If you were to use the above function in your VBA code, the function would always return the range of cells A1 to G4 in whichever sheet you are working in.

Calling a Function from a Sub Procedure

Once you create a function, you can call it from anywhere else in your code by using a Sub Procedure to call the function.

The value of 50 would always be returned.

You can also call the GetRange function from a Sub Procedure.

In the above example, the GetRange Function is called by the Sub Procedure to bold the cells in the range object.

Creating Functions

Single Argument

You can also assign a parameter or parameters to your function. These parameters can be referred to as Arguments.

We can then call the above function from a Sub Procedure in order to work out how many pounds a specific amount of kilos are.

A function can be a called from multiple procedures within your VBA code if required. This is very useful in that it stops you from having to write the same code over and over again. It also enables you to divide long procedures into small manageable functions.

In the above example, we have 2 procedures – each of them are using the Function to calculate the pound value of the kilos passed to them in the dblKilo Argument of the function.

Multiple Arguments

You can create a Function with multiple arguments and pass the values to the Function by way of a Sub Procedure.

We can then call the function to calculate the amount of days between 2 dates.

Optional Arguments

You can also pass Optional arguments to a Function. In other words, sometimes you may need the argument, and sometimes you may not – depending on what code you are using the Function with .

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Default Argument Value

You can also set the default value of the Optional arguments when you are creating the function so that if the user omits the argument, the value that you have put as default will be used instead.

ByVal and ByRef

When you pass values to a function, you can use the ByVal or ByRef keywords. If you omit either of these, the ByRef is used as the default.

ByVal means that you are passing a copy of the variable to the function, whereas ByRef means you are referring to the original value of the variable. When you pass a copy of the variable (ByVal), the original value of the variable is NOT changed, but when you reference the variable, the original value of the variable is changed by the function.

In the function above, the ByRef could be omitted and the function would work the same way.

To call this function, we can run a sub-procedure.

Note that the debug windows show the value 40 both times. When you pass the variable IntVal to the function – the value of 10 is passed to the function, and multiplied by 4. Using the ByRef keyword (or omitting it altogether), will AMEND the value of the IntVal variable. This is shown when you show first the result of the function in the immediate window (40), and then the value of the IntVal variable in the debug window (also 40).

If we do NOT want to change the value of the original variable, we have to use ByVal in the function.

Now if we call the function from a sub-procedure, the value of the variable IntVal will remain at 10.

Exit Function

If you create a function that tests for a certain condition, and once the condition is found to be true, you want return the value from the function, you may need to add an Exit Function statement in your Function in order to exit the function before you have run through all the code in that function.

The function above will loop through the string that is provided until it finds a number, and then return that number from the string. It will only find the first number in the string as it will then Exit the function.

The function above can be called by a Sub routine such as the one below.

Using a Function from within an Excel Sheet

In addition to calling a function from your VBA code using a sub procedure, you can also call the function from within your Excel sheet. The functions that you have created should by default appear in your function list in the User Defined section of the function list.

Click on the fx to show the Insert Function dialog box.

Select User Defined from the Category List

Select the function you require from the available User Defined Functions (UDF’s).

Alternatively, when you start writing your function in Excel, the function should appear in the drop down list of functions.

If you do not want the function to be available inside an Excel sheet, you need to put the Private word in front of the word Function when you create the function in your VBA code.

It will now not appear in the drop down list showing the Excel functions available.

Interestingly enough, however, you can still use the function – it just will not appear in the list when looking for it!

If you have declared the second argument as Optional, you can omit it within the Excel sheet as well as within the VBA code.

You can also use the a function that you have created without arguments in your Excel sheet.

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Simply navigate to the menu, click, and the code will be inserted directly into your module. .xlam add-in.

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