Android Question parameters in subs

[Markos]

Hi All,

I have what may be a fundamental question to most avid b4a developers but I was wondering if the following code would update the byte array buff1 and if the code is correct. If not for a byte array would it update a basic type such as int or string etc?

sub check
dim buff1() as byte

checkthis (buff1)
msgbox(buff1(1),"Test")
end sub

sub checkthis(buff2() as byte)
buff2(0)=56
buff2(1)=99
end sub

 

[Roycefer]

Did you try it?

In Java (and therefore B4J and B4A), objects are passed by reference and primitives are passed by value. Arrays are objects, so they are passed by reference, meaning that buff2 in your checkthis sub is a reference to the same array as buff1 in your sub check.

 

[Johan Schoeman]

Hi All,

I have what may be a fundamental question to most avid b4a developers but I was wondering if the following code would update the byte array buff1 and if the code is correct. If not for a byte array would it update a basic type such as int or string etc?

sub check
dim buff1() as byte

checkthis (buff1)
msgbox(buff1(1),"Test")
end sub

sub checkthis(buff2() as byte)
buff2(0)=56
buff2(1)=99
end sub

The call should be
buff1 = checkthis(buff1)

The sub must also specify the return type eg:
Sub checkthis(buff2() as byte) as byte
buff2(0) = 56
buff2(1) = 99
return buff2
end sub

 

[Markos]

The call should be
buff1 = checkthis(buff1)

The sub must also specify the return type eg:
Sub checkthis(buff2() as byte) as byte
buff2(0) = 56
buff2(1) = 99
return buff2
end sub

Oh that looks great. I will try that to update the variable proper. I was gonna do that but thought it may have been redundant. Kool.

Cheers

 

[klaus]

The Sub declaration must be:
Sub checkthis(buff2() As Byte) As Byte()
It needs () at the end because it returns an array.

 

[Markos]

Oh yes quite right.

Cheers