Re: Controlling width of strings during Put operation?

["Robert I. Eachus" <rieachus@comcast.net>]

Peter C. Chapin wrote:

> My issue is: how do I best print the table headers? I could certainly 
> play around with spaces until I got good looking results but that seems 
> fragile and inelegant. I'd rather set a field width for each header 
> based on the Num'Width of the numeric type in the column below that 
> header. That way if I change the type of one of the columns, the headers 
> have a prayer of still lining up without me fiddling with them again. My 
> problem is that I don't see a Put procedure that allows me to specify a 
> field width when I print a string. Do I have to "manually" prepare my 
> own header strings with the appropriate number of padding spaces? Is 
> there an easy way to do that?

Yes. I would use Ada.Strings.Fixed.Trim (see 
http://www.adaic.org/standards/95lrm/html/RM-A-4-3.html)

with Ada.Strings.Fixed;
with Ada.Text_IO;
...
function Pad(Header: in String; Size: Positive := Integer'Width) return 
String is
   use Ada.Strings, Ada.Strings.Fixed;
   Result: String(1..Size);
begin
   Move(Source => Header,
        Target => Result,
        Drop => Right,
        Justify => Center,
        Pad => Space);
    -- or of course, whatever values you want.
    return Result;
end Pad;

Now of course you just write your header line something like:

Ada.Text_IO.Put_Line( Pad("Column 1") & Pad("Column 2") & ...);

I often think that there should be a function form of Move, in 
Ada.Strings.Fixed.  But since it is usually much more convenient to use 
the above technique to reset some of the defaults anyway, I don't get 
too upset about it.

-- 
                                           Robert I. Eachus

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