OpenCV Study, Merging to extended Mat from 2 Mat (example source code)

Example of merging to extended Mat from 2 Mat

For example,
A=[1 2 3; 4 5 6];
B=[7 8 9; 3 2 1];
C=[A; B];  < - how to make this merging Mat??

refer to this example source code.

---

Mat A(3, 10, CV_32F);
 Mat B(4, 10, CV_32F);

 int cnt=0;
 for(int i=0; i< A.rows; ++i)
 {
  for(int j=0; j< A.cols; ++j)
  {
   A.at< float>(i,j) = float(i*j);
  }
 }

 cout << "A" << endl;
 cout << A << endl << endl;
 
 for(int i=0; i< B.rows; ++i)
 {
  for(int j=0; j< B.cols; ++j)
  {
   B.at< float>(i,j) = float(i*j)*10;
  }
 }

 cout << "B" << endl;
 cout << B << endl << endl;
 


 Mat C(A.rows + B.rows, A.cols, CV_32F);
 memcpy(C.data, A.data, sizeof(float) * A.cols * A.rows );
 int startP = sizeof(float) * A.cols * A.rows;
 memcpy(&(C.data[ startP ]), B.data, sizeof(float) * B.cols * B.rows );

 cout << "C = [A; B]" << endl;
 cout << C << endl << endl;

...
The result of example source code..