Re: Data conversion

Re: Data conversion

[David C. Hoos, Sr.]

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Mat & Syl wrote in message <71fcr5$9to@sifon.cc.mcgill.ca>...
>I need a function to convert float to string and other one for string to
>float.
The language attributes 'Image, and 'Value, respectively, do just that.

Here are the appropriate excerpts from Annex K of the Ada95 Reference
Manual:

88 S�Image For every scalar subtype S:

89 S�Image denotes a function with the following specification:

90 function S'Image(Arg : S'Base)
return String

91 The function returns an image of the value of Arg as a String. See 3.5.

264 S�Value For every scalar subtype S:

265 S�Value denotes a function with the following specification:

266 function S'Value(Arg : String)
return S'Base

267 This function returns a value given an image of the value as a String,
ignoring any leading or trailing spaces. See 3.5.

David C. Hoos, Sr.

Data conversion

[Mat & Syl]

I need a function to convert float to string and other one for string to
float.

            Thanks

Re: Data conversion

[dewarr]

In article <71fcr5$9to@sifon.cc.mcgill.ca>,
  "Mat & Syl" <slambe@po-box.mcgill.ca> wrote:
> I need a function to convert float to string and other one for string to
> float.


I wonder why this is such a FAQ, when the answer is right there in the
language, namely the Image and Value attributes which of course provide
exactly this functionality. At least in my case when I am teaching Ada, I
teach people about the Image attribute very early (this is my preferred
method for doing integer output for Text_IO, since, unlike Integer_Text_IO it
keeps working fine for derived types when you get to them).



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Re: Data conversion

[Pascal MALAISE]

Mat & Syl wrote:
> 
> I need a function to convert float to string and other one for string to
> float.
> 
>             Thanks
text_io (83) or Ada.Text_IO.Float_IO (95)

private generic
   type Num is digits <>;
package Ada.Text_IO.Float_IO is
...
   procedure Get
     (From : in String;
      Item : out Num;
      Last : out Positive);

   procedure Put
     (To   : out String;
      Item : in Num;
      Aft  : in Field := Default_Aft;
      Exp  : in Field := Default_Exp);
...

-- 
Pascal MALAISE
(priv) mailto:malaise@magic.fr
(prof) mailto:malaise@fr.airsysatm.thomson-csf.com

Re: Data conversion

[dewarr]

In article <363B5ADC.8639CEB0@magic.fr>,
  Pascal MALAISE <malaise@magic.fr> wrote:
> Mat & Syl wrote:
> >
> > I need a function to convert float to string and other one for string to
> > float.
> >
> >             Thanks
> text_io (83) or Ada.Text_IO.Float_IO (95)
>
> private generic
>    type Num is digits <>;
> package Ada.Text_IO.Float_IO is
> ...
>    procedure Get
>      (From : in String;
>       Item : out Num;
>       Last : out Positive);
>
>    procedure Put
>      (To   : out String;
>       Item : in Num;
>       Aft  : in Field := Default_Aft;
>       Exp  : in Field := Default_Exp);
> ...
>
> --
> Pascal MALAISE
> (priv) mailto:malaise@magic.fr
> (prof) mailto:malaise@fr.airsysatm.thomson-csf.com


This is a frequent answer o this FAQ, but for most purposes it is not the
most convenient answer, ESPECIALLY for input, where 'Value is far better.
Usually 'Image is more convenient for output, but of course Put to a string
is more appropriate if you need to control the format.


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