how to make vector of vectors c++ code example

Example 1: how to create a vector in c++

// CPP program to create an empty vector 
// and push values one by one. 
#include <vector>

using namespace std;
int main() 
{ 
    // Create an empty vector 
    vector<int> vect;  
    //add/push an integer to the end of the vector
    vect.push_back(10); 
	//to traverse and print the vector from start to finish
    for (int x : vect) 
        cout << x << " ";

    return 0; 
}

Example 2: create vectors of vectors c++

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

Matrix matrix = { {0.1,1.1,.2},
                 {.4,.5,.6}, 
                 {.8,.9,.10}
                };
// Just initilization:
int rows = 3;
int cols = 3;
Matrix m3(rows, std::vector<double>(cols) );