Help with Text_IO Instantiation!

Help with Text_IO Instantiation!

[Robert Gelb]

I have the following code:

procedure test is 
	type string is array(integer range 1..10) of character;
	type SaType is array(integer range <>) of string;
	StrArray:SaType(1..5);

	begin
		put(StrArray(1));
end test;		

What kind of Text_IO instatiation do I need to specify in order to make
'put(StrArray(1));' statement work.

I've tried 
	with Ada.Text_Io, Ada.Integer_Text_Io;
	use  Ada.Text_Io, Ada.Integer_Text_Io;
but it doesn't seem to work with the type of string I declared.  I am
using ADA95.

Re: Help with Text_IO Instantiation!

[Robert Dewar]

There is no built in Put for user defined string types, you will have
to program it yourself.

Re: Help with Text_IO Instantiation!

[David Weller]

In article <4llqlg$i49@newsbf02.news.aol.com>,
John Herro <johnherro@aol.com> wrote:
>rgelb@csulb.edu (Robert Gelb) wrote:
>> type string is array(integer range 1..10) of character;
>> type SaType is array(integer range <>) of string;
>> StrArray:SaType(1..5);
>> begin
>>    put(StrArray(1));.
>> What kind of Text_IO instatiation do I need to
>> make 'put(StrArray(1));' work?

[Good advice from John trimmed...]
>ever, want to define your own string type.  *Subtypes* of the built-in
>type String are perfectly OK, and, since subtypes do not create a new
>type, Ada.Text_IO works fine for them.
>     I hope this helps, and I hope it clears up more confusion than it
>causes!
>- John Herro
>Software Innovations Technology
>http://members.aol.com/AdaTutor
>ftp://members.aol.com/AdaTutor

What John means, of course, is that you want to probably do something
like this:
procedure sub is

   subtype Tiny_String is String(1..12);

   type Tiny_Array is array(integer range <>) of Tiny_String;

   TA : Tiny_Array(1..10);
begin
   TA(1) := "Ohmygoodness";
   put_Line(Ta(1));
end sub;

Note that you could not simply declare:
   type Tiny_Array is array(String) of Tiny_String;
Because String is an unconstrained array.

-- 
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           This is not your father's Ada -- lglwww.epfl.ch/Ada

Re: Help with Text_IO Instantiation!

[John Herro]

rgelb@csulb.edu (Robert Gelb) wrote:
> type string is array(integer range 1..10) of character;
> type SaType is array(integer range <>) of string;
> StrArray:SaType(1..5);
> begin
>    put(StrArray(1));.
> What kind of Text_IO instatiation do I need to
> make 'put(StrArray(1));' work?
     Robert Dewar's answer is entirely correct, but allow me to add some
comments.  In writing
type string is array(integer range 1 .. 10) of character;
you're doing two potentially confusing things which beginners should avoid
and even veteran programmers should do very rarely, if at all.  First,
you've chosen a name, string, which is *already defined* by the Ada
language.  In doing this, you "hide" the definition of String built into
Ada, namely
type String is array(Integer range <>) of Character;
This is asking for confusion.  You don't need to declare type String in
your program because it's already defined by the language.  Second, you
declared a new *type* when it appears that what you want to declare is a
*subtype*.  Since you use your declaration only in the following line to
declare SaType, I think what you meant to do was:
subtype String10 is String(1 .. 10);
type SaType is array(Integer range <>) of String10;
Now your Put statement will work fine, with no instantiations necessary. 
Incidentally, it's legal to combine the above two lines into one as
follows:
Type SaType is array(Integer range <>) of String(1 .. 10);
Also, note that Ada.Text_IO itself is not generic, but ready-to-use for
the type String built into the language.  Therefore, Ada.Text_IO itself
needs no instantiation.  Inside Ada.Text_IO are generic packages for
integers, floats, enumeration types, etc. that can be instantiated with
approprate user-defined types, but there's no package ready to be
instantiated with a user-defined string type, because you would rarely, if
ever, want to define your own string type.  *Subtypes* of the built-in
type String are perfectly OK, and, since subtypes do not create a new
type, Ada.Text_IO works fine for them.
     I hope this helps, and I hope it clears up more confusion than it
causes!
- John Herro
Software Innovations Technology
http://members.aol.com/AdaTutor
ftp://members.aol.com/AdaTutor