1. Functions
Chapter 6-Part 2

2. Functions Built-in Function Examples Functions don’t stand alone.
Val(txtTextBox.Text)
InputBox(“Prompt”)
Functions don’t stand alone.
intAge = Val(txtAge.Text)
Chapter 6 Part 2

3. Function Information Similar to General Procedure
Set of statements that perform a task when called
Not associated with controls
Parameter lists like general sub procedures
Local variables allowed
Different from General Procedure
The function must return a value result used in an expression.
Function name is a variable in itself.
Chapter 6 Part 2

4. Differences between Procedure & Function
Does not return a value; can pass values by reference or value though.
Returns a value to its call statement.
Called procedure can be on its own line.
Invokes function but must contain code on same line to do something with returned value.
Use when end result is not just a single value.
Use when end result is a single value.
Chapter 6 Part 2

5. Process Encounters function call.
Invokes function (and passes any arguments).
Completes function code.
Returns a value through the name of the function.
Stores function value in something—a variable.
Chapter 6 Part 2

6. Function Syntax Access: Private, Public, etc.
[Access] Function FunctionName(ParameterList) As DataType
[Statements]
End Function
Access: Private, Public, etc.
Function: specifies function
FunctionName: name of function you create
ParameterList: variables declared to receive arguments passed; specifiy ByVal or ByRef
As DataType: declaration of function return type
Chapter 6 Part 2

7. Function Header Function Name Parameter passed by value Return Type
Chapter 6 Part 2

8. Function Example: Return Value Through Return Keyword
Parameter variable to
receive a copy of
the incoming argument
Local
variable
Contents of local variable returned
Return keyword returns value to the function call.
Chapter 6 Part 2

9. Alternative Function: Assign Value to Function Name
Chapter 6 Part 2

10. Function Call Syntax Variable = FunctionName(arguments)
Variable stores results of function
FunctionName calls (invokes) the function
Arguments variables passed to the function
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11. decShipping ShippingCharge decPurchase
Variable to store results of function
ShippingCharge
Function call
decPurchase
Variable to pass as argument to function
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12. Process (10 contained in decPurchase variable)
Step 4
Step 3
Step 1
Step 1: Passes 10 by value to the function.
Step 2: Select Case determines shipping is 2.95.
Step 3: 2.95 returned through function name to calling statement.
Step 4: 2.95 return value is assigned to decShipping variable.
Chapter 6 Part 2

13. Function Return Value Stored in Variable
Chapter 6 Part 2

14. Function Notes The function name is a “store-only” variable.
The function name value contains the value at the end of the function.
A function never is displayed on the right side of an assignment statement inside that function. Doing so would invoke itself (the function) again.
Chapter 6 Part 2

15. Additional Return Information
Also return nonnumeric results
String
Boolean (pp )
Chapter 6 Part 2

16. Section 6.6
Read scenario, study sketches, examine methods and flowcharts, and interpret pseudocode.
Build application (Tutorial 6-7).
Chapter 6 Part 2