VB6 - Basics 4 - What's the function of that sub?

[Jacob]

Subs and function are the backbone of the program.

A function will return a value and a sub will not.

Sub

Code:

Public Sub Foo()
End Sub

Function
It is advised to give a return variable to your function. Below will return a Long variable.

Code:

Public Function Foo() as Long
End Function

ByVal and ByRef
ByVal: ByValue - will make a local copy of the variable. Meaning if you change the value you are not changing the original value.
ByRef: By Reference - It is similar to a pointer in c++. If you change the value of the variable, the original value will change.

Optional
An optional argument is just that, you don't have to pass anything into that sub or function. When declaring an optional argument, it is best practice to give it a default value.

Code:

Public Function Foo(Optional ByVal val As Long = 1) As Long
End Function

Project

Code:

Private Sub Command1_Click()
    Dim i As Long
    i = 3
    Foo i
    
    Dim ii As Long
    ii = Bar(i)
End Sub

Public Sub Foo(ByRef val As Long)
    val = val + 1
End Sub

Public Function Bar(ByVal val As Long) As Long
    Bar = val + 1
End Function

What will 'i' and 'ii' equal ? Explain why they will equal what they do.

Now program a small calculator. You must be able to input any 2 numbers and use all basic math operators (+,-,/,*). The user must be able to pick what mathematical operator to use.

Overview

• Input 2 numbers.
  
• Must have all basic math operators - (+,-,/,*)
  
• User must be able to pick which mathematical operator to use.

Notes

• Make sure to comment your code.

[Pbcrazy]

Very nice tuts!

But if i may suggest, put all of these into a seperate sub-board. Like VB6 Basic's or something.

[Pbcrazy]

Please don't tell me I have to complete them...

But i agree with Asrrin none the less.