How to Define a Template Typedef for a Modified Template Class in C ?

How to Define a Template Typedef for a Modified Template Class

Consider a template class Matrix with type parameters N and M. To create a "Vector" (column vector) with dimensions equivalent to Matrix, a typedef is desired:

typedef Matrix<N,1> Vector<N>;

However, this approach leads to a compile error.

Alternative and Solution

C 11 introduces alias declarations that generalize typedef and allow templating:

template <size_t N>
using Vector = Matrix<N, 1>;

In C 11 and later, the type Vector<3> is equivalent to Matrix<3, 1>.

Workaround for C 03

Prior to C 11, the following is a close approximation:

template <size_t N>
struct Vector
{
    typedef Matrix<N, 1> type;
};

Here, Vector<3>::type is equivalent to Matrix<3, 1>.

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