Hi, I like to print the strings from a C function that returns const(dchar*), but I can't make the conversion to dstring. I can convert vice versa by:

dstring text = "Hello";
const(dchar)* str = toUTFz!(const(dchar)*)(text);
// passing it to C function prints Hello

However, I don't have the idea how can I go the other way. I tried several methods such as using to!dstring, toUTF32 etc which compiles successfully however printing them gives address of them instead of text.

Thanks,

Danyal Zia

On Tue, 24 Jun 2014 13:37:41 -0400, Danyal Zia <catofdanyal@yahoo.com> wrote:

> Hi, I like to print the strings from a C function that returns const(dchar*), but I can't make the conversion to dstring. I can convert vice versa by:
>
> dstring text = "Hello";
> const(dchar)* str = toUTFz!(const(dchar)*)(text);
> // passing it to C function prints Hello
>
> However, I don't have the idea how can I go the other way. I tried several methods such as using to!dstring, toUTF32 etc which compiles successfully however printing them gives address of them instead of text.

const(dchar *)x = ...;

// assuming 0 terminated
dstring text = x[0..x.strlen].idup;

-Steve

On Tuesday, 24 June 2014 at 17:59:41 UTC, Steven Schveighoffer wrote:
> const(dchar *)x = ...;
>
> // assuming 0 terminated
> dstring text = x[0..x.strlen].idup;
>
> -Steve
const(dchar)* x = "Hello\0";
dstring text = x[0..x.strlen].idup;
writeln(text);

Error: no property 'strlen' for type 'const(dchar)*'

On Tuesday, 24 June 2014 at 17:59:41 UTC, Steven Schveighoffer wrote:
> // assuming 0 terminated
> dstring text = x[0..x.strlen].idup;

strlen is only defined for char, not dchar:
https://github.com/D-Programming-Language/druntime/blob/master/src/core/stdc/string.d#L44

On Tuesday, 24 June 2014 at 18:17:07 UTC, Danyal Zia wrote:
> On Tuesday, 24 June 2014 at 17:59:41 UTC, Steven Schveighoffer wrote:
>> const(dchar *)x = ...;
>>
>> // assuming 0 terminated
>> dstring text = x[0..x.strlen].idup;
>>
>> -Steve
> const(dchar)* x = "Hello\0";
> dstring text = x[0..x.strlen].idup;
> writeln(text);
>
> Error: no property 'strlen' for type 'const(dchar)*'

You can do what he said, but you'll have to write your own strlen function:

something like:

    size_t strlen(in dchar* s) pure @system nothrow
    {
        size_t pos = 0;
        dchar term = '\0';
        while(s[pos] != term)
            ++pos;
        return pos;
    }
    const(dchar)* ds = "hello\0";
    dstring text = ds[0..strlen(ds)].idup;
    writeln(text);

works

On Tue, 24 Jun 2014 18:17:06 +0000, Danyal Zia wrote:

> On Tuesday, 24 June 2014 at 17:59:41 UTC, Steven Schveighoffer wrote:
>> const(dchar *)x = ...;
>>
>> // assuming 0 terminated dstring text = x[0..x.strlen].idup;
>>
>> -Steve
> const(dchar)* x = "Hello\0";
> dstring text = x[0..x.strlen].idup;
> writeln(text);
> 
> Error: no property 'strlen' for type 'const(dchar)*'

A dchar* strlen implementation: http://dpaste.dzfl.pl/a4053387d8a4

On Tuesday, 24 June 2014 at 18:34:31 UTC, Chris Cain wrote:
> You can do what he said, but you'll have to write your own strlen function:
>
> something like:
>
>     size_t strlen(in dchar* s) pure @system nothrow
>     {
>         size_t pos = 0;
>         dchar term = '\0';
>         while(s[pos] != term)
>             ++pos;
>         return pos;
>     }
>     const(dchar)* ds = "hello\0";
>     dstring text = ds[0..strlen(ds)].idup;
>     writeln(text);
>
> works
It works indeed, thanks a lot! Any chance of making it into std phobos?

On Tue, 24 Jun 2014 14:28:58 -0400, Chris Cain <zshazz@gmail.com> wrote:

> On Tuesday, 24 June 2014 at 17:59:41 UTC, Steven Schveighoffer wrote:
>> // assuming 0 terminated
>> dstring text = x[0..x.strlen].idup;
>
> strlen is only defined for char, not dchar:
> https://github.com/D-Programming-Language/druntime/blob/master/src/core/stdc/string.d#L44
>

Right, I forgot about that.

-Steve