c++ 'CA2W': identifier not found

Question

why do i get 'CA2W': identifier not found

for(DWORD i = 0; i < numMaterials; i++)    // for each material...
    {
        material[i] = tempMaterials[i].MatD3D;    // get the material info
        material[i].Ambient = material[i].Diffuse;    // make ambient the same as diffuse
        USES_CONVERSION;    // allows certain string conversions
        // if there is a texture to load, load it
        D3DXCreateTextureFromFile(d3ddev,
                                            CA2W(tempMaterials[i].pTextureFilename),
                                            &texture[i]);
        texture[i] = NULL;    // if there is no texture, set the texture to NULL
      }

Answer 1

Show us your code, otherwise we are powerless to help you.

The error you are getting means: "What the heck is CA2W???"

It means you are using the identifier CA2W, but it hasn't been declared as anything.

Answer 2

CA2W is defined in <atlconv.h>.

Answer 3

So try this - Create a Win32 console project, then replace the given code with this below that compiles fine for me. If this does not compile for you, I'm stumped - perhaps re-install Visual Studio? Seems like multiple people can compile this properly, so what might be wrong with your Visual Studio installation?

// testconv.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <atlconv.h>
#include <atlbase.h> 
#include <atlstr.h>

int _tmain(int argc, _TCHAR* argv[])
{
   USES_CONVERSION;
   WCHAR *pChar = CA2W(NULL);
    return 0;
}

Answer 4

Edit:

The OP has just told me that Visual Studio 2010 Express was used to compile the code. That would explain why CA2W couldn't be found, because the Express editions do not include the entire ATL/MFC library. Therefore, my original answer is irrelevant to the OP.

The moral of the story: make sure to mention exactly what environment you're on when asking these kinds of questions.

Instead of using CA2W, you can use MultiByteToWideChar() - this function is what's actually being used by CA2W to convert the string, so you'll get basically the same result.

Here's a usage example of MultiByteToWideChar() in an answer to another Stack overflow question. It's for a conversion from std::string to LPCWSTR, but it's basically the same process.

Original answer:

According to the documentation for ATL and MFC String Conversion Macros you must include:

#include <atlbase.h>
#include <atlconv.h>

int main()
{ 
    // Explicitly qualified the CA2W identifier
    ATL::CA2W("Hello World!"); // Test to see if this compiles
} 

I think the reason why this code snippet didn't work before was because you #define'd _ATL_NO_AUTOMATIC_NAMESPACE somewhere before #include <atlbase.h>.

Answer 5

Check if the path to the ATL header files atlconv.h and atlbase.h is visible to Visual Studio

In your monopoly.cpp file, right-click on the line #include <atlconv.h> and select Open document atlconv.h. If the header file opens properly, then it means there is no problem with the location. Instead, if it throws an error, then it means VStudio cannot locate the file and that's the reason why it says 'identifier not found'.

In the error message, VStudio displays the path to the folders where it looked for the header file. Check if the list contains a path similar to "C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\ce\atlmfc\include", where the ATL header files are present. If it is missing, include the path (use the path appropriate to your OS and the version of VStudio that you are using) as follows: Visual Studio: Tools->Options->Projects and Solutions->VC++ Directories-> "Show directories for Include files".