Question

I’d like to know if there is a way to call a timer through a function. This function itself is called through an automated timer that is activated when the form loads.

Function callTimer(ByRef var1 As Integer, ByVal var2 As Integer)
    'statements()
    Media.SystemSounds.Beep.Play() 'to ensure that it is called
    Call otherFunction(ByRef var3 As Integer) <-- how do you do this??
    Return var1
End Function

I want to know how this can be done. VB gives me an error when I try this or something like this.

Thanks all!

Answer 1

What @competent_tech was saying is that you’re defining a function within a function, which is illegal. You want to call the function, not define it. An example of this would be like so:

Shared _timer As Timer 'this is the timer control

Function callTimer(ByRef var1 As Integer, ByVal var2 As Integer)
    Media.SystemSounds.Beep.Play() 'to ensure that it is called
    Dim testInt As Integer
    testInt = 4
    Call otherFunction(testInt) '<-- this calls otherFunction and passes testInt
    Return var1
End Function

Function otherFunction(ByRef var3 As Integer)
    StartTimer(var3) ' this will start the timer and set when the timer ticks in ms
                ' (e.g. 1000ms = 1 second)
End Function

'this starts the timer and adds a handler. The handler gets called every time 
'the timer ticks
Shared Sub StartTimer(ByVal tickTimeInMilliseconds As Integer)
    _timer = New Timer(tickTimeInMilliseconds)
    AddHandler _timer.Elapsed, New ElapsedEventHandler(AddressOf Handler)
    _timer.Enabled = True
End Sub
'this is the handler that gets called every time the timer ticks
Shared Sub Handler(ByVal sender As Object, ByVal e As ElapsedEventArgs)
    ' . . . your custom code here to be called every time the timer tickets
End Sub

It seems like you might be a little confused with calling a function versus defining a function. Before you can use a function it must be defined, like my example code above.

Another thing to get a better handle on is the usage of ByRef versus ByVal. ByRef passes a reference to an address in memory. What this means is that any changes to the variable within a function will persist outside of the function. ByVal, however, will not persist outside of the function and the value before being passed to the function will be the same as after the function call. Here is an example of that:

Sub Main()
    Dim value As Integer = 1

    ' The integer value doesn't change here when passed ByVal.
    Example1(value)
    Console.WriteLine(value)

    ' The integer value DOES change when passed ByRef.
    Example2(value)
    Console.WriteLine(value)
End Sub

'any Integer variable passed through here will leave unchanged
Sub Example1(ByVal test As Integer)
    test = 10
End Sub

'any Integer variable passed through here will leave with a value of 10
Sub Example2(ByRef test As Integer)
    test = 10
End Sub

Result:

test = 1

test = 10

This ByRef/ByVal example can be seen at this link. It’s worth looking more into if you’re still confused.

EDIT: This edit includes information regarding invoking a timer in VB.NET.