Re: %str(%addr()) vrs direct value reference.

[Barbara Morris <bmorris@xxxxxxxxxx>]

Paul.Thieme@xxxxxxxxxxxxxxxxx wrote:
> ...
> Everything works fine.   My problem is I don't understand what
> %str(%addr(d_name)) is doing and why it is needed.
>
> Walking through the program in debug, I noticed that d_name has a value.  I
> changed the code to the "easier on the eyes" version which is simply taking
> a 256 char field and truncating it in a 120 char field.
> ...

Paul, readdir() returns a null-terminated string in d_name.  The x'00' 
character is the null-terminator.  In the debugger (see below), this 
character looks like a blank, but you can see it in the hex output if 
you use
  eval d_name:x

The %STR builtin function looks for the null-terminator and ignores 
everything after it.

It looks like both %STR and %SUBST are equally valid ways of handling 
the output of readdir.  (Assuming that it's impossible for a directory 
name to be longer than 639.)

In this debugger session, you can see the '00' in the second line of the 
hex listing for d_name:x

> EVAL d_name
  D_NAME =
            ....5...10...15...20...25...30...
       1   '/home/mydir/a.txt

> EVAL d_name:x
     00000     61889694 856194A8 848999...
     00010     A3004040 40404040 404040...