Question

I have a list of files I need to open in a certain function via a LPCSTR argument, but unfortunately they’re located in certain folders (subdirectories of the main program root) with a very long path, and I don’t want to type it in every time I want to pass the filenames.

To be more precise, I have the function D3DXCreateTextureFromFile() which asks for the filename, and for example, I have the files a.png, b.png, c.png located in the “…\Materials\Textures\Textures_For_This\Textures_For_That\More_Specific_Texture_Location\” subdirectory of the main program. How can I register this path and add it to the filename argument in a lean and mean way?

Like some sort of this:

D3DXCreateTextureFromFile(bla, **DECLARED_DIR** + a.png, bla)
//same for b.png, c.png

Or even a subfunction that unifies the path and the filename:

D3DXCreateTextureFromFile(bla, UnifyText(DECLARED_DIR, a.png), bla)

Answer 1

Yep, easiest to make a function to combine the directory with the filename and include separator if required. Because you want to pass this as an argument, you want to avoid allocating a string and having to clean it up… So use the C++ string class.

I generally do something like this:

string TexturePath( LPCSTR filename = NULL )
{
    if( filename == NULL ) return string(TEXTURE_DIR);
    return string(TEXTURE_DIR) + "\" + filename;
}

Of course, you’ll be relying on that string being implicitly cast to LPCSTR later. If you want to be more explicit then do the (slightly ugly) call to string::c_str():

D3DXCreateTextureFromFile(bla, TexturePath("a.png").c_str(), bla)

[Edit]

Another way, if you are doing this single-threaded, is to use a static buffer:

LPCSTR TexturePath( LPCSTR filename = NULL )
{
    static char pathBuf[MAX_PATH];
    if( filename == NULL ) return TEXTURE_DIR;
    sprintf( pathBuf, "%s\\%s", TEXTURE_DIR, filename );
    return pathBuf;
}