class within a class in C++

knobby67 · 07-21-2009, 05:14 AM

SOLVED sorry can't delete

Hi all,
I'm a fairly advanced C programmer but have little experience in C++, and need to convert some code to C++, basically I have 3 "nested classes" but am having trouble calling a variable from the "inner class".
Basically "main" class is MD5ModelLoader, then I have a class for mesh

class Mesh
{
public:
std ::vector<Texture> textures;
std ::vector<vertecies> verts;
//etc.......

};

and a texture class

class Texture
{
public:
std::string texture_name;

}

so if I want to display texture string I do

mesh->textures.texture_name=shader_from_file;

printf("shader name %s \n",mesh->texture.texture_name.c_str());

This gives me
error : 'class std :: vector<MD5ModelLoader::Texture, std::<MD5ModelLoader::Texture> >' has no member named 'texture_name'

It looks like it's not seeing mesh class, but I know it is because the vettecies class works fine :s

normally I'd do these as structures but need to use C++, can anyone advise. Thanks.

pilotmm · 07-21-2009, 05:42 PM

Forgive me for my post, I didn't realize you found a solution. None the less, this will give a solution to other confused readers.

Hi knobby67

The problem is with this line:

Quote:

mesh->textures.texture_name=shader_from_file;

Let me explain how this compiles:

1) ``mesh->textures'' compiles into the ``textures'' within Mesh which is of type ``std::vector<Texture>''
2) Then the compiler attempts to access ``.texture_name'' from that object.

Problem is that since this is of type ``std::vector<Texture>'', not type ``Texture'' the compiler doesn't know what you are reffering to and throws an error. instead of ``.texture_name'' you need to select what ``Texture'' you want within textures.

Translating into C talk:

Code:

struct texture{
   char* texture_name;
};

struct Mesh{
   texture* textures;
};

main()
{
    struct Mesh *mesh;

    mesh=(struct Mesh *)malloc(sizeof(struct Mesh);
    mesh->textures=(texture*)malloc(N*sizeof(texture))

    mesh->textures.texture_name=shader_from_file;    // WRONG!!
    mesh->textures[n].texture_name=shader_from_file; // Right
}

Does that make sense?

Good luck
pilotmm