vector initialization c++ 2d code example

Example 1: initialize 2d vector of ints c++

auto M = 4;	// num of rows
auto N = 3; // num of cols in each row
auto default_value = 1; // default value of all int elements
std::vector<std::vector<int>> matrix(M, std::vector<int>(N, default_value));

Example 2: initialzing a 2d vector in cpp

// Create a vector containing n row and m columns
  vector<vector<int> > vec( n , vector<int> (m, 0));

Example 3: 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*/