使用Cuffic函数操作C++中模板类中的私有变量时出错

我最近正在写一个矩阵运算库,我想在程序中重载运算符s,但是当我使用friend函数访问我定义的模板类中的私有变量时出错了。(而且它只在重载运算符“+”时报告错误,而重载操作“-”的函数不报告错误。) 我定义的模板类如下:

template<class T>
class Matrix
{
    int col;
    int row;
    T *matrix;
    public:
        Matrix(T *m, int row1, int col1):matrix(m), row(row1), col(col1){}
        Matrix(int row1, int col1):row(row1), col(col1)
        {
            matrix = new T[row*col];
            cout<<"Have set the shape of the matrix, but should use create() to initialize the matrix!"<<endl;
        }
        Matrix(){}
        ~Matrix(){}
        void show();
        UINT create(T *m);
        UINT zeros(int size);
        UINT eye(int size);

        // the overload function statement
        friend Matrix operator+(const Matrix &a, const Matrix &b);
        friend Matrix operator-(const Matrix &a, const Matrix &b);

        Matrix matrix_T();              // transpose the matrix
        Matrix matrix_Inv();            // calculate matrix's inverse
        Matrix matrix_Adjoint();        // calculate the adjoint matrix
};

这两个重载函数的定义如下:

// report error: can't access private member declared in class
template<class T>
Matrix<T> operator +(const Matrix<T> &m1, const Matrix<T> &m2)
{
    if (m1.col!=m2.col || m1.row!=m2.row)
    {
        cout<<"These two matrices can't be plused!"<<endl;
        exit(0);
    }
    T *tmp = new T[m1.col*m1.row];
    for (int i=0; i<m1.row; i++)
    {
        for (int j=0; j<m1.col; j++)
        {
            tmp[i*m1.col+j] = m1.matrix[i*m1.col+j] + m2.matrix[i*m1.col+j];
        }
    }
    return Matrix<T>(tmp, m1.row, m1.col);
}


// this defination didn't report error
// and if I only run this code, there is nothing wrong
template<class T>
Matrix<T> operator -(const Matrix<T> &m1, const Matrix<T> &m2)
{
    if (m1.col!=m2.col || m1.row!=m2.row)
    {
        cout<<"These two matrices can't be plused!"<<endl;
        exit(0);
    }
    T *tmp = new T[m1.col*m1.row];
    for (int i=0; i<m1.row; i++)
    {
        for (int j=0; j<m1.col; j++)
        {
            tmp[i*m1.col+j] = m1.matrix[i*m1.col+j] - m2.matrix[i*m1.col+j];
        }
    }
    return Matrix<T>(tmp, m1.row, m1.col);
}

我已经分别测试了这两段代码,运算符“-”的重载可以正确编译,但运算符“+”不能。 误差信息如下:

f:\program\c++\matrixoperate\matrixdefine.h(134) : error C2248: 'col' : cannot access private member declared in class 'Matrix<int>'
    f:\program\c++\matrixoperate\matrixdefine.h(6) : see declaration of 'col'
    f:\program\c++\matrixoperate\demo.cpp(14) : see reference to function template instantiation 'class Matrix<int> __cdecl operator +(const class Matrix<int> &,const class Matrix<int> &)' being compiled
f:\program\c++\matrixoperate\matrixdefine.h(134) : error C2248: 'col' : cannot access private member declared in class 'Matrix<int>'
    f:\program\c++\matrixoperate\matrixdefine.h(6) : see declaration of 'col'

我使用的IDE是VC++ 6。