Strings initialised by literals

Strings initialised by literals

[Matthew Woodcraft]

I've a feeling this question came across this newsgroup recently, but
I've been unable to find the thread.

If I write

      Sample : String := "example";

Gnat tells me that Sample'First is 1. Is this guaranteed by the
langauge, or does the compiler choose?

-M-

Re: Strings initialised by literals

[James Rogers]

This is guaranteed by the language.

The string type is defined as :

type string is array(Positive range <>) of character;

Jim Rogers
Colorado Springs, Colorado

Matthew Woodcraft wrote:
> 
> I've a feeling this question came across this newsgroup recently, but
> I've been unable to find the thread.
> 
> If I write
> 
>       Sample : String := "example";
> 
> Gnat tells me that Sample'First is 1. Is this guaranteed by the
> langauge, or does the compiler choose?
> 
> -M-

Re: Strings initialised by literals

[Tucker Taft]

James Rogers wrote:

> This is guaranteed by the language.
>
> The string type is defined as :
>
> type string is array(Positive range <>) of character;

Not all strings start at 1.  However, when there is no "applicable index
constraint" provide by context, then the low bound is the lower bound of
the index subtype, which in this case is Positive (and Positive'First =
1).
See RM95 4.3(26).

> Jim Rogers
> Colorado Springs, Colorado
>
> Matthew Woodcraft wrote:
> >
> > I've a feeling this question came across this newsgroup recently, but
> > I've been unable to find the thread.
> >
> > If I write
> >
> >       Sample : String := "example";
> >
> > Gnat tells me that Sample'First is 1. Is this guaranteed by the
> > langauge, or does the compiler choose?
> >
> > -M-

-Tucker Taft  stt@avercom.net

Re: Strings initialised by literals

[James Rogers]

I agree completely. However, the specific question asked about the
lower bound for a string literal. This should fall into the no
"applicable index constraint" exception you mentioned below.
For that reason I said the lower bound will be 1.

Jim Rogers
Colorado Springs, Colorado USA

Tucker Taft wrote:
> 
> James Rogers wrote:
> 
> > This is guaranteed by the language.
> >
> > The string type is defined as :
> >
> > type string is array(Positive range <>) of character;
> 
> Not all strings start at 1.  However, when there is no "applicable index
> constraint" provide by context, then the low bound is the lower bound of
> the index subtype, which in this case is Positive (and Positive'First =
> 1).
> See RM95 4.3(26).
> 
> > Jim Rogers
> > Colorado Springs, Colorado
> >
> > Matthew Woodcraft wrote:
> > >
> > > I've a feeling this question came across this newsgroup recently, but
> > > I've been unable to find the thread.
> > >
> > > If I write
> > >
> > >       Sample : String := "example";
> > >
> > > Gnat tells me that Sample'First is 1. Is this guaranteed by the
> > > langauge, or does the compiler choose?
> > >
> > > -M-
> 
> -Tucker Taft  stt@avercom.net

Re: Strings initialised by literals

[Larry Kilgallen]

In article <3B5B7E39.79B814F4@avercom.net>, Tucker Taft <stt@avercom.net> writes:
> 
> 
> James Rogers wrote:
> 
>> This is guaranteed by the language.
>>
>> The string type is defined as :
>>
>> type string is array(Positive range <>) of character;
> 
> Not all strings start at 1.  However, when there is no "applicable index
> constraint" provide by context, then the low bound is the lower bound of
> the index subtype, which in this case is Positive (and Positive'First =
> 1).
> See RM95 4.3(26).

Actually 4.3.3(26), I presume (now that you have pointed it out).