typedef模板类错误

Question

I have the following class

template < int rows, int columns >
class Matrix
{
    //stuff
};

I am doing the following:

typedef Matrix<4,4> Matrix3D;

However I am getting errors when I declare the following in another class:

class Transform3D
{
public:
    Matrix3D matrix;
        //some other stuff
};

The errors I see are:

error C2146: syntax error : missing ';' before identifier 'matrix'
error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
error C4430: missing type specifier - int assumed. Note: C++ does not support default-int

all these are at line 7 which is:

    Matrix3D matrix;

This is in VS 2010. What could be the issue?

Answer 1

I have created project with only one file and it did compile

template < int rows, int columns >
class Matrix
{
   //stuff
};

typedef Matrix<4,4> Matrix3D; 

class Transform3D
{
public:
     Matrix3D matrix;
     //some other stuff
};

void main()
{
}

Thus, I think the problem is related to the usage of precompiled headers. Can you tell more about how your files are organized?

Answer 2

From your explanation I assume the following setup:

stdafx.h

// ..
typedef Matrix<4,4> Matrix3D; 
// ..

Matrix.h

template < int rows, int columns > class Matrix { /*...*/ };

Transform.h

class Transform3d { Matrix3D matrix; /*...*/ };

Transform.cpp

#include "stdafx.h"

If this is the case, the class Transform3D doesn't seem the definition of Matrix template, (I would expect that the typedef in stdafx.h to generate a compilation error, but I am not very familiar with precompiled headers in Visual Studio).

You should #include file Matrix.h in file Transform.h and move the typedef from stdafx.h in Transform.h. Or... you should include Matrix.h in stdafx.h, but I would do that only if you that header file is stable enough (to ensure you still take advantage of precompiled headers).

My prefered way:

stdafx.h

// ..
// typedef Matrix<4,4> Matrix3D; -- removed from here
// ..

Matrix.h

template < int rows, int columns > class Matrix { /*...*/ };

Transform.h

#include "Matrix.h"

typedef Matrix<4,4> Matrix3D; 

class Transform3d { Matrix3D matrix; /*...*/ };