推断类型:decltype()的简单应用

Posted 2021-03-01 lhb666aboluo

template<class T, class U>
auto operator+(const Matrix<T>& a, const Matrix<U>& b) -> Matrix<decltype(T{}+U{})>
{
    Matrix<decltype(T{}+U{})> res;
    for(int i=0; i!=a.rows(); ++i)
        for(int j=0; j!=a.cols(); ++j)
            res(i,j) += a(i,j)+b(i,j);
    return res;
}