declaring a 2d vector in c++ code example

Example 1: how to get size of 2d vector in c++

myVector[
  Vector[0, 4, 2, 5],
  Vector[1, 4, 2]
];

/*When you call for myVector[1].size() it would return 3 and [0] would return 4.

For the amount of rows (int vectors) in the 2d vector, you can just use myVector.size()

You can run this to see it in actions*/

Example 2: size of a matrix using vector c++

// finding size of a square matrix
myVector[0].size();

Example 3: initialising 2d vector

// Initializing 2D vector "vect" with 
// values 
vector<vector<int> > vect{ { 1, 2, 3 }, 
                           { 4, 5, 6 }, 
                           { 7, 8, 9 } };