Re: Leading zeros with Int_IO.Put()? Or another package?

[Ken Garlington <garlingtonke@lmtas.lmco.com>]

robin wrote:
> 
> dewar@merv.cs.nyu.edu (Robert Dewar) writes:
> 
>         >robin says
> 
>         >>"Interface to PL/I and you can use standard I/O:
> 
>         >>put edit (n) (P'-99999999');
> 
>         >>and you don't have to worry about whether the number is
>         >>negative either.  The nines in the picture format
>         >>force leading zeros to print.
> 
>         >>And if you want, you can insert commas in the output
>         >>to make it more readable.  The picture specification becomes:
> 
>         >>P'-999,999,999'"
> 
>         >I guess robin knows PL/1 and does not know Ada!
> 
>         >If you want to use picture editing to solve this kind of problem, then
>         >use the picture editing in Ada, no need to wander off into PL/1, even in
>         >the unlikely case that you have a PL/1 compiler at hand. Personally I
>         >dislike the picture stuff in PL/1, they tried to improve on COBOL and
>         >made a mess of it.
> 
> Isn't it amazing!  Robert Dewar [among others] already has
> had an opportunity to reply in this vein to the original
> posting and subsequent ones, but it didn't occur to him to
> do so, more than likely because he didn't know that a limited
> facility existed in Ada.  Instead, he suggested using
> string facilities.

Actually, if you know Ada, it's not amazing at all. The Ada picture I/O is for
decimal types; the original request was for integer types. If you don't want to
convert your type, the suggestion by Dr. Dewar is more straight-forward. If you
do want to use picture I/O, you probably still want to use an abstraction of
this facility to hide the details of type conversion, instantiation of picture I/O,
etc.

Ada people have this perversity of suggesting the most straight-forward and
maintainable approach first. :)

> 
> Below is Robert Dewar's previous posting:
> 
> >This is a place where CLEARLY there is a missing abstraction (Put with
> >leading zeros), and it seems obvious that you fix this in the way that
> >you always do abstraction extension, you create an appropriate abstraction
> >and use it. If it is useful enough, hopefully it gets to be widely available.
> 
> >Note that if you do want to construct on the fly, a much clearer way is to
> >use the string routines from the string packages, which have padding
> >capabilities.
> 
> PL/I is not restricted to picture editing with decimal data,
> (one poster suggested changing to Ada decimal data in order to use
> Ada's limited editing).   PL/I requires *only* the single line:
> 
> put edit (n) (P'-99999999');
> 
> and not the (up to) page of Ada code to implement the
> requirement of the original post.

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