Android Question can i set/change a variable when i pass it as parameter ?

[Addo]

i am trying to create a sub in another Module to set some local variables in a parameter

as example

dim var as string

setvarstring(var)

log(var) 'This should be = something  can i do that ?


sub setvarstring(avar as string)

avar = "something"

end sub

 

[lucasheer]

Basic4android follows Java parameter passing. Objects are passed by reference and "primitives" are passed by value.
Arrays are objects so are always passed by reference.

ByVal vs ByRef

Maybe I something in the documentation, Ive noticed in my applications that that when I call a Sub routine the "variables" that are passed are a reference to the variable. WHich is the default for VB6 as well. My question is, how to I pass a copy of the variable? The ByVal would achive this...

www.b4x.com

Since 'avar' is a string, it's being passed as a value. If you want to change the value of that specific variable, you'll have to reference it through it's module.

OR

return the value and change it from the original module:

Dim var As String

var = setvarstring(var)

Log(var) 'This should be = something  can i do that ?


Sub setvarstring(avar As String)

    Return "something"

End Sub

 

[Addo]

then i should return it as string ? i cant set it directly without using return ?

 

[lucasheer]

then i should return it as string ? i cant set it directly without using return ?

You can reference the other module like:

Sub setvarstring(avar As String)

    othermodule.var = "something"

End Sub

The problem is that it's passing your string as a value instead of a reference. Look at ByRef vs ByVal

 

[Brian Dean]

i am trying to create a sub in another Module ...

You cannot do this in the way you illustrate, as I think that you understand (arguments are passed by value). But there are alternative ways to get values into one module from another - global variables are the obvious one, but using a class object with properties (which are in fact subroutines in another module) is often a better scheme.

 

[Erel]

i am trying to create a sub in another Module to set some local variables in a parameter

Declare a custom type with all the fields and pass it, or better create a sub that creates one and returns it.

In some esoteric cases where it does make sense to pass variables by reference then you can use arrays:

Dim str(1) As String
SomeSub(str)

Sub SomeSub(str() As String)
 str(0) = "aaa"
End Sub