Android Question Passing String 'ByRef'

Alwinl

Member
Licensed User
Longtime User
I have read the tutorial on this and I have the understanding that primitives are passed by value and all others by reference, and that strings are not primitives. This is my code :

s1 = "abc"
SetVal(s1)
log(s1) 'I'd expect this to print 'xyz' but it prints 'abc'

sub SetVal(s2 as string)
s2 = "xyz"
end sub

So either a string is a primitive and is passed by value, or passing ByRef is not supported in this sense.
 

sirjo66

Well-Known Member
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Longtime User
In this moment I can't try it, so may be that this don't work, but you can try with:

sub SetVal(ByRef s2 as string)
s2 = "xyz"
end sub

Sergio
 
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Erel

B4X founder
Staff member
Licensed User
Longtime User
1. There is no ByRef in Basic4android.
2. Strings are immutable objects. You cannot modify an existing string object. What you are doing is you are assigning a new object to the variable. It will not have any effect on any other variables (assuming that it is a local variable).
You can pass a custom type that holds a string:
B4X:
Type StrRef (s As String)
This will allow you to pass the StrRef object and change its value.

You can also pass an array with a single string.

Last option is to pass a StringBuilder instead of String. Then you will be able to remove its current content and append the new content.
 
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