Re: Structures with byte arrays using fromstring cause segfault

[Jussi Lahtinen <jussi.lahtinen@xxxxxxxxx>]

Here is your code corrected:

Public Struct demo
     tag[100] As Byte
End Struct

Public dtag As Struct Demo
Public theString As String = "This is a test string tag"

Public Sub main()

     dtag.tag.fromstring(theString)

     Print "Tag="; dtag.tag.tostring()

     For i As Integer = 0 To theString.len - 1
        dtag.tag[i] = Asc(theString[i])
     Next
     dtag.tag[i + 1] = 0

     Print "Tag="; dtag.tag.tostring()

End

However, the fromstring() function still does nothing.


Jussi


On Sun, May 19, 2024 at 11:36 PM Brian G <brian@xxxxxxxxxxxxxxxx> wrote:

> When Working with structures with byte arrays, the copy of a string to
> the byte array
> using fromstring() appears to corrupt memory
>
> But using the tostring() seems to work correctly.
>
> I have included  a simple script to demonstrate the issue.
> The first line does a fromstring() and initially appears to do nothing.
>
> But the last line that frees the allocated memory causes a segfault
> sometimes.
>
> Removing the line doing the fromstring() makes everything ok on the free.
>
> Maybe I am using this in an incorrect way?
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> #!/usr/bin/env gbs3
>
> public struct demo
>      tag[100] as byte
> end struct
>
> public dtag as demo = alloc(400)
> public theString as string = "This is a test string tag"
>
> public sub main()
>      dtag.tag.fromstring(theString)
>
>      print "Tag=";dtag.tag.tostring() ' prints nothing and in fact the
> content is not changed.
>
>      for i as integer = 0 to theString.len-1
>         dtag.tag[i] = asc(theString[i])
>      next
>      dtag.tag[i+1]=0
>
>      print "Tag=";dtag.tag.tostring()
>
>      free(varptr(dtag))
> end
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
> --
> ~~~~ Brian
>
>