C++模版－重载，嵌套

#include 
using namespace std;

template<typename T>
class CArray3D{
public:
    class CArray2D{
    public:

        CArray2D(){
            ptr = NULL;
        }
        void initCArray2D(int a, int b);

        T* operator[](int i);

        T& operator[](int i) const;

    private:
        T **ptr;
        int size;
        int curcol;
        int col;
        int row;
    };


    CArray3D(int a, int b, int c);

    CArray2D& operator[](int i);

private:
    CArray2D* ptr;
    int size;
    int curcol;
    int col;
    int row;
    int x;
    int y;
    int z;
};

template<typename T>
void CArray3D::CArray2D::initCArray2D(int a, int b){
    ptr = new T*[a];
    size = a*b;
    for(int i=0;inew int[b];
    col = a;
    row = b;
    curcol = -1;
}

template<typename T>
CArray3D::CArray3D(int a, int b, int c):x(a), y(b), z(c){
    size = a;
    ptr = new CArray2D[a];
    for(int i = 0; i < a; i++)
        (ptr+i)->initCArray2D(b,c);
    curcol = -1;
}

template<typename T>
typename CArray3D::CArray2D& CArray3D::operator[](int i){
    curcol = i;
    return *(ptr+i);
}

template<typename T>
T& CArray3D::CArray2D::operator[](int i) const{
    return *(*(ptr+curcol)+i);
}

template<typename T>
T* CArray3D::CArray2D::operator[](int i){
    curcol = i;
    return *(ptr+i);
}



int main()
{
    CArray3D<int> a(3,4,5);
    //CArray3D a(3,4,5);
    int No = 0;
    for( int i = 0; i < 3; ++ i )
        for( int j = 0; j < 4; ++j )
            for( int k = 0; k < 5; ++k )
                a[i][j][k] = No ++;
    for( int i = 0; i < 3; ++ i )
        for( int j = 0; j < 4; ++j )
            for( int k = 0; k < 5; ++k )
                cout << a[i][j][k] << ",";
    return 0;
}