Is there any way to define wchar[] literals?

I need this:
wchar[] format(wchar[] fmt, ...);
togeteher with standard:
char[] format(char[] fmt, ...);

Also following produces compilation error "cannot cast..."
bool convertTo(int i, inout wchar[] ws) { ws = i? "true":"false"; return
true; }

Thanks.

Andrew Fedoniouk wrote:

> Is there any way to define wchar[] literals?

Yes: cast(wchar[]) "string"

I know, I know... :-)

There has been a suggestion to bring back the
C syntax for declaring wide strings: L"string"
(would be the same as: cast(wchar[]) "string")
Or maybe another letter, like w"string" perhaps?

But so far it hasn't been popular... (with W)

BTW;
wchar[] s = "string"; // works without cast()

 --anders

On Fri, 6 May 2005 23:36:13 -0700, Andrew Fedoniouk wrote:

> Is there any way to define wchar[] literals?

Yes. But it's not neat or intuitive given that syntax is available for writing 'wide' integers and floating point values.

  cast(wchar[])"This is a Wide String Literal";

But please beware of a syntactical anomaly; you cannot do this to char[] variables and get a wchar[].

   char[] A = "An ASCII string";
   wchar[] W;

   W = cast(wchar[])A;  // WRONG!

This time the cast makes 'W' point to A's data and has D pretending it is a wide string, but no data conversion has actually happened.

   W = std.utf.toUTF16(A); // CORRECT!

This is the correct way to convert narrow string variables to wide strings.

So to summarize, use 'cast(wchar[])' on narrow string literals and
'std.utf.toUTF16()' on narrow string variables.

Why Walters isn't interested in adding a qualifier on string literals such as he has for numbers is hard for me to understand.

-- 
Derek Parnell
Melbourne, Australia
http://www.dsource.org/projects/build v2.06 is now available. 04/May/2005
7/05/2005 7:55:33 PM

Derek Parnell wrote:

> But please beware of a syntactical anomaly; you cannot do this to char[]
> variables and get a wchar[].
> 
>    char[] A = "An ASCII string";
>    wchar[] W;
> 
>    W = cast(wchar[])A;  // WRONG!
> 
> This time the cast makes 'W' point to A's data and has D pretending it is a
> wide string, but no data conversion has actually happened.
> 
>    W = std.utf.toUTF16(A); // CORRECT!
> 
> This is the correct way to convert narrow string variables to wide strings.

You can also do this: (but only with literals)

    char[] A = "An ASCII string";
    wchar[] W = "An ASCII string";

    char[] A = "A non-ASCII string (€)";
    wchar[] W = "A non-ASCII string (€)";

And the same goes for non-literal conversions:

    A = cast(char[]) W; // WRONG
    A = std.utf.toUTF8(W); // CORRECT


Note:
Sometimes you have to cast "" into char[], like if you
have a function overloaded with both char[] and wchar[] ?
(Phobos uses a "W" prefix/suffix on wchar[] functions...)

The string literals in D are of an *unnamed* string type.
They are not of the type "char[]", like one might expect...
(since e.g. the integer and floating literals are typed ?)

--anders

Thanks, guys,

> cast(wchar[]) "string"

Aha, I suspected trap like this, but hope dies last...

Andrew.


"Andrew Fedoniouk" <news@terrainformatica.com> wrote in message news:d5hnl6$24gn$1@digitaldaemon.com...
> Is there any way to define wchar[] literals?
>
> I need this:
> wchar[] format(wchar[] fmt, ...);
> togeteher with standard:
> char[] format(char[] fmt, ...);
>
> Also following produces compilation error "cannot cast..."
> bool convertTo(int i, inout wchar[] ws) { ws = i? "true":"false"; return
> true; }
>
> Thanks.
>