On Friday, March 02, 2012 05:51:14 Chris Pons wrote:
> Hello,
> I am trying to work with SDL and one of their functions takes a
> char * file as a function a parameter. However, i'm running into
> trouble how to actually set this variable in my constructor.
>
> I am getting a problem where if I use a pointer to a char and set
> it as "test.bmp" I get an error stating "cannot implicitly
> convert expression (file) of type string to char*. After that I
> decided to try to set file to 'test.bmp' instead, and in that
> case I get: "Unterminated character constant" . Although I am
> familiar with what this error is referring to, I do not know how
> to add a terminator in D.
>
> This is the function that I intend to use the filename in:
> **Note the function LoadBMP is the one that REQUIRES a pointer to
> a char
> --------------------------------------
> SDL_Surface * Load(char * file)
> {
> SDL_Surface * Temp = null;
>
> if((Temp = SDL_LoadBMP(file)) == null)
> return null;
>
> Surface = SDLDisplayFormat(Temp);
>
> SDL_FreeSurface(Temp);
>
> return Surface;
> }
> ----------------------------------------
>
> This is the constructor that is giving me the error:
> ----------------------------------------------------------
> char * file;
>
> this()
> {
> this.filename = "test.bmp";
> }
> -------------------------------------------------------------
Use std.string.toStringz (or std.utf.toUTFz if immutable(char)* doesn't cut
it).
Regardless, be careful of passing char* to C code. Even if the C code keeps
the pointer, it won't stop the GC from collecting it. The D code needs to have
reference to it of some kind (though a pointer in your struct as you appeart
to be doing should be plenty as long as an instance of the struct remains in
the D code - as opposed to passing it to the C code and then not having it in
the D code anymore, which would be no better than just passing the char* to
the C code without keeping a reference to it).
- Jonathan M Davis
