unit 6: functions and subroutines

Excel Macros Level 1

Functions and Subroutines

M. Campbell - 2010 2

Functions & Subroutines

Functions: Return a value

Subroutines Do not return a value

Both are used to: Make code modular (i.e. reusable) Make code more readable

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p. 69


Activities

In the Unit 6 Activities complete: Activity 1: Uppercase Subroutine Activity 2: Lowercase Subroutine Activity 3: Title Case Subroutine Activity 4: Uppercase Function

Note that these can all go in the same module

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Functions

In Activity 4 you saw the function declaration:

Public Function Uppercase2(Text As String) _As String

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Functions



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Indicates the Function's scope:Public:

Can be called from any modulePrivate:

Can only be called from module it was declared in

p. 76


Functions



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Declares this code to be a Function

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Functions



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The Function's nameThis is something that you define

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Functions



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This is the Function's Parameter listValue is a ParameterWhen you ran the Function, the value of Text was set

to helloThe value placed in a Parameter is known as an

Argument

p. 71


Functions


Public Function Uppercase2(Text As String) _ As String

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This is the Function's Return TypeIn this Function, it will return a value of type String

p. 69


Functions

In Activity 4 you saw this line of code:

Uppercase2 = UCase(Text)

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Functions



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This is the Function's Return statementThe value of the expression on the right side of the

assignment operator will be returned by the Function


Functions



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Remember that Text is the parameter to the Function.

It currently holds the value of helloThis sends the value to the UCase Function which

converts hello to uppercase


Subroutines

In Activity 1 you saw the subroutine declaration:

Sub Uppercase()

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Subroutines


Sub Uppercase()

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Declares this code to be a Subroutine

p. 70


Subroutines


Sub Uppercase()

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The Subroutine's nameThis is something that you define

p. 70


Subroutines


Sub Uppercase()

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Note the absence of the scope keyword Public or Private

If it is omitted, the procedure (subroutine or function) is declared to be Public

It should always be included for readability

p. 76


Calling Subroutines

Has the form:[Public or Private] Sub SubroutineName (_Param1 As DataType1, Param2 As DataType2,_ …)

To call:Call SubroutineName(parameters, …)

OrSubroutineName parameters, …4/29/2010

p. 70


Activities

In the Unit 6 Activities complete: Activity 5: Calling a Function with a Subroutine

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Optional Arguments

Can set some arguments to be optional

Sub DisplayName(firstName As String, _Optional lastName As

String, _Optional midName As String)

Note that all optional arguments must come at end of parameter list

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p. 71


Optional Arguments

Sub DisplayName(firstName As String, _Optional lastName As String, _Optional midName As String)

To call procedure with only firstName and midName:Call DisplayName("Winnie", , "the")

Must include blank spot as arguments expected in order defined in parameter list

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p. 71


Positional Arguments

In previous example, we used positional arguments:

Call DisplayName("Winnie", , "the") The position of arguments tells VBA which parameters

they fill

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p. 73


Named Arguments

Naming the arguments: Improves readability Removes the need for blank spaces Allows arguments to go in any order

Call DisplayName(midName:= "the", _ firstName:= Winnie")

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p. 73


Activities

In the Unit 6 Activities complete: Activity 6: Optional and Named Arguments

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ByRef

Sub ProcedureA()x = 5MsgBox xCall AddOne(x)MsgBox x

End Sub

Sub AddOne(ByRef i As Integer)i = i + 1

End Sub

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ByRef


End Sub


End Sub

p. 73

Initializes x to 5


ByRef


End Sub


End Sub

p. 73

Displays 5


ByRef


End Sub


End Sub

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Calls AddOne and sends x


ByRef


End Sub


End Sub

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AddOne is sent a reference to x, effectively replacing the i with x


ByRef


End Sub

Sub AddOne(ByRef x As Integer)x = x + 1

End Sub

p. 73

AddOne is sent a reference to x, effectively replacing the i with x


ByRef


End Sub

Sub AddOne(ByRef x As Integer)x = x + 1

End Sub

p. 73

1 is added to x to get 6This is the same x as in ProcedureA

unit 6: functions and subroutines

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