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Understanding Functions, Arguments, and Procedures in Programming

This guide explores the fundamental concepts of functions, arguments, and procedures in programming. It explains how to pass information to procedures using arguments in parentheses, with practical examples. You'll learn about the ByVal and ByRef keywords, highlighting the differences in passing data by value versus by reference. The document provides clear examples for creating and using functions, including return values and static variables. Enhance your programming skills and understand how to manipulate and manage data seamlessly in your applications.

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Understanding Functions, Arguments, and Procedures in Programming

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  1. Functions • Using arguments and sub procedures: • You can pass information to a procedure by enclosing the arguments in parentheses Callmysub(aninteger, astring) ‘ 2 arguments, an integer ‘ and a string Sub mysub(ByVal aninteger as integer, ByVal astring as string) Text1.text = aninteger & “ “ & astring  End Sub

  2. Functions • You can pass variables, constants, values or expressions Call Myproc(2*5, 300)

  3. Functions • Example: Private Sub mysub(ByVal aninteger As _ Integer, ByVal astring As String) Text1.Text = astring & " has an average of " & aninteger End Sub

  4. Functions • Example: Private Sub Command1_Click() Call mysub(75, "John Doe") End Sub

  5. Functions

  6. Functions • ByVal --- passes a copy of the information to the procedure. • The data passed can be modified but it is not reflected in the called procedure

  7. Functions • ByRef --- the parameter is passed by reference. Refer to an arguments memory location Dim ANumber as Integer ANumber=998 pass(ANumber) Text1.text= ANumber  You can only pass variable data types BY REFERENCE

  8. Functions ‘ anint is 998 before this function is called Public Sub pass(ByRef anint As Integer) anint = anint + 1 End Sub ‘ anint is now 999 AFTER this function executes

  9. Functions Function: • A special type of procedure • Functions can return a value

  10. Functions function funname (byValarg1 as type, arg2 byRef as type) as returntype

  11. Functions function ff_calc(var1, var2) as integer … ff_calc = var1 + var2 ‘ return value exit function ‘ early end to function end function ‘ end of function

  12. Functions in my program… text1.text = ff_calc(10, 20)   What Number appears ? 30

  13. Functions Static Variables: •  A Local variable that maintains it STATE •  Local In scope but its value persists until the form or program is unloaded

  14. Functions Private Sub Command1_Click() Static x As Integer x = x + 1 Text1.Text = x

  15. Functions BOWLING PROJECT

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