Putting a 'Duration' on the screen ?

Putting a 'Duration' on the screen ?

[Emmanuel Lambert]

Hi,

I am freaking out because I would like to output a variable from type
Duration to the screen, but it does not work with put(...). I have
included Ada.Float_Text_Io, but that does not help. Can someone give me
a hint. I a unable to find good documentation on this.

Thanks
Emmanuel Lambert

Re: Putting a 'Duration' on the screen ?

[robert_dewar]

In article <36A37529.69BFB3FF@cs.kuleuven.ac.be>,
  Emmanuel Lambert <Emmanuel.Lambert@cs.kuleuven.ac.be>
wrote:
> Hi,
>
> I am freaking out because I would like to output a
> variable from type Duration to the screen, but it does
> not work with put(...). I have included
> Ada.Float_Text_Io, but that does not help. Can someone
> give me a hint. I a unable to find good documentation on
> this.


Emmanuel, so that you may avoid freaking in the future,
let's help you to figure out how to find your own answer
next time :-)

First, look up type Duration in the reference manual, a
little searching in the RM (I always use the ASCII version
it is easier for me to search) finds:

  7   There is a predefined fixed point type named
      Duration, declared in the visible part of package
      Standard;

Ah ha! A *fixed point* type not a *floating point* type.
A little more spelunking around in Text_IO digs up:

68     generic
          type Num is delta <>;
       package Fixed_IO is

71        procedure Put(File : in File_Type;
                        Item : in Num;
                        Fore : in Field := Default_Fore;
                        Aft  : in Field := Default_Aft;
                        Exp  : in Field := Default_Exp);


and if you know how to use generics you are pretty much
home free now. But actually there is an even easier way,
and here again is how you could find this. Look up
operations on a fixed point type, and you will find the
Image attribute, just what the doctor ordered, now you
can do

   Put_Line (Duration'Image (xxx));

which is probably good enough for what you want, though
you don't have control over the format as you do with
Text_IO.

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Re: Putting a 'Duration' on the screen ?

[Emmanuel Lambert]

Thanks to all for the valuable feedback!!

Re: Putting a 'Duration' on the screen ?

[Tom Moran]

ada.text_io.put("That took" & duration'image(d) & "seconds");

Re: Putting a 'Duration' on the screen ?

[Steve O'Neill]

Emmanuel Lambert wrote:

> I am freaking out because I would like to output a variable from type
> Duration to the screen, but it does not work with put(...). I have
> included Ada.Float_Text_Io, but that does not help. Can someone give me
> a hint.

The hint is - Duration is not a floating point type, it's a fixed point
type.  Either instantiate Fixed_IO for Duration or convert the duration
object to float.

Re: Putting a 'Duration' on the screen ?

[Matthew Heaney]

Steve O'Neill <oneills@top.monad.net> writes:

> Emmanuel Lambert wrote:
> 
> > I am freaking out because I would like to output a variable from type
> > Duration to the screen, but it does not work with put(...). I have
> > included Ada.Float_Text_Io, but that does not help. Can someone give me
> > a hint.
> 
> The hint is - Duration is not a floating point type, it's a fixed point
> type.  Either instantiate Fixed_IO for Duration or convert the duration
> object to float.

No, do not convert Duration to float.

You can either:

1) Use an instantiation of Ada.Text_IO.Fixed_IO; or

2) Use the attribute Duration'Image (X).

The 2nd option is easier.


-- 
Those who believe in the supernatural should be required to learn
computer programming.  This would force them to discover that things
which appear at first to be completely mysterious and incomprehensible,
in fact have a logical (and usually simple) explanation.  --J.B.R. Yant

Re: Putting a 'Duration' on the screen ?

[Marin David Condic]

Ada.Float_Text_IO doesn't work because Duration is not a floating point
type. It is a fixed point type. You've got two choices here:

with Ada.Text_IO.Fixed_IO ;
procedure Blah_Blah_Blah is
    package
        My_Fixed_IO
    is new
        Ada.Text_IO.Fixed_IO (
            Num => Duration) ;
    --  After this, you have a procedure My_Fixed_IO.Put you can call...
...
...
...
*OR*

Ada.Text_IO.Put_Line ("Current Duration: " & Duration'Image (X)) ;

where X above is declared to be of type Duration. The numeric types have
the 'Image attribute which will return a string. See the ARM 3.5 (35)
for a definition.

Hope this helps.

MDC


Emmanuel Lambert wrote:
> 
> Hi,
> 
> I am freaking out because I would like to output a variable from type
> Duration to the screen, but it does not work with put(...). I have
> included Ada.Float_Text_Io, but that does not help. Can someone give me
> a hint. I a unable to find good documentation on this.
> 
> Thanks
> Emmanuel Lambert

-- 
Marin David Condic
Real Time & Embedded Systems, Propulsion Systems Analysis
United Technologies, Pratt & Whitney, Large Military Engines
M/S 731-95, P.O.B. 109600, West Palm Beach, FL, 33410-9600
Ph: 561.796.8997         Fx: 561.796.4669
***To reply, remove "bogon" from the domain name.***

    "Nobody shot me."

        --  Last words of Frank Gusenberg when asked by police who
            shot him fourteen times with a machine gun in the Saint
            Valentine's Day Massacre.

Re: Putting a 'Duration' on the screen ?

[David C. Hoos, Sr.]

Marin David Condic wrote in message <36A38F05.EA6F4DD1@pwfl.com>...
<SNIP>
>where X above is declared to be of type Duration. The numeric types have
>the 'Image attribute which will return a string. See the ARM 3.5 (35)
>for a definition.
A slight correction -- all _scalar_ types have a 'image attribute.

Re: Putting a 'Duration' on the screen ?

[Marin David Condic]

David C. Hoos, Sr. wrote:
> 
> Marin David Condic wrote in message <36A38F05.EA6F4DD1@pwfl.com>...
> <SNIP>
> >where X above is declared to be of type Duration. The numeric types have
> >the 'Image attribute which will return a string. See the ARM 3.5 (35)
> >for a definition.
> A slight correction -- all _scalar_ types have a 'image attribute.

I stand corrected. Enumerations also include the 'Image attribute.

Anyway, it's the easiest way of getting something out to the screen -
especially when you're in a hurry and don't care too much about spacing.

I'm sure this question must be in the FAQ by now. But I suppose it won't
stop being asked since newbies are also frequently newbies to FAQs as
well. Maybe if CS profs made a little more effort to cover this, the
students wouldn't be so confused?

MDC
-- 
Marin David Condic
Real Time & Embedded Systems, Propulsion Systems Analysis
United Technologies, Pratt & Whitney, Large Military Engines
M/S 731-95, P.O.B. 109600, West Palm Beach, FL, 33410-9600
Ph: 561.796.8997         Fx: 561.796.4669
***To reply, remove "bogon" from the domain name.***

    "Nobody shot me."

        --  Last words of Frank Gusenberg when asked by police who
            shot him fourteen times with a machine gun in the Saint
            Valentine's Day Massacre.