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From: Robert A Duff <bobduff@shell01.TheWorld.com>
Newsgroups: comp.lang.ada
Subject: Re: String literals and wide_string literals - how?
Date: Fri, 20 Apr 2007 10:55:45 -0400
Organization: The World Public Access UNIX, Brookline, MA
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Date: 2007-04-20T10:55:45-04:00
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Gerd <GerdM.O@t-online.de> writes:

> Hi all,
>
> if I have a string, then I can write a literal simply by writing
> "abcd". But if I want write a wide_string literal, how do it?

Same syntax.  Context determines the type.

String literals are not necessarily of type String; they can be of any
"string type".  A string type is any one-dimensional array of some
character type.  You can even do weird things like this:

    type Bit is ('0', '1');
    type Bit_String is array (Positive range <>) of Bit;
    pragma Pack(Bit_String);
    X: constant Bit_String := "01011110";

Bit is a character type, and Bit_String is a string type.

X can fit in 8 bits, by the way.

> Assume I have two procedure of the form:
>
> procedure do_anything (s : string);
>
> procedure do_anything (w : wide_string);
>
> then
>
> do_anything ("abcd");
>
> would call the first one.

No, this is ambiguous, and therefore illegal.

>... What would one write to call the second
> one?

To call either one, you need to qualify the type of the parameter:

    Do_Anything(String'("abcd"));
    Do_Anything(Wide_String'("abcd"));
    Blah: Wide_String := "abcd";
    Do_Anything(Blah);

> Is there something like the L"xxx" in C?

That sort of syntax wouldn't work in Ada, because there are an unbounded
number of string types.  The qualified_expression syntax --
"type_name'(expression)" is used instead.

- Bob