push_back 将向量的向量转换为向量

Question

How to create a vector of matrices (vector of vectors) where the matrices are of different size and initialized?

typedef std::vector<double> Vector;
typedef std::vector<std::vector<double>> Matrix;

Vector v;
std::unique_ptr<Matrix> m = std::make_unique<Matrix>();
(*m)[0][0] = 1.0; 
v.push_back(m);

Compilation error:

vectors.cpp: In function 'int main()':
vectors.cpp:37:18: error: no matching function for call to 'std::vector<double>::push_back(std::uniq
ue_ptr<std::vector<std::vector<double> > >&)'
     v.push_back(m);
                  ^

Answer 1

You need to use something along the lines of:

typedef std::vector<std::vector<double>> Matrix;
typedef std::vector<std::unique_ptr<Matrix>> MatrixVector;

std::unique_ptr<Matrix> m = std::make_unique<Matrix>();
MatrixVector mv;
mv.push_back(std::move(m));

Answer 2

Change type Vector to:

typedef std::vector<std::unique_ptr<Matrix>> Vector;

then you can push_back it,

v.push_back(std::move(m));

BTW: (*m)[0][0] = 1.0; is UB. You might use push_back to add element.

Answer 3

Arrange your typedefs thus:

typedef std::vector<std::vector<double>> Matrix;
typedef std::vector<std::shared_ptr<Matrix>> Vector;

Note the use of shared_ptr - this makes it easier to transfer ownership of the Matrix into the Vector .

Then:

Vector v;
std::shared_ptr<Matrix> m = std::make_shared<Matrix>();
// Add content to the matrix... 
v.push_back(m);