In C++, you can use a vector to store elements in a dynamically resizable array. A 2D vector is simply a vector of vectors, where each inner vector represents a row of elements.

To add elements to a 2D vector, you can follow these steps:

1. Declare the 2D vector:

   std::vector<std::vector<int>> matrix;
   

2. Add elements to the 2D vector:

   matrix.push_back({1, 2, 3});     // Adds a new row {1, 2, 3}
   matrix.push_back({4, 5, 6});     // Adds a new row {4, 5, 6}
   

You can also add elements individually to a specific row:

matrix[0].push_back(7);          // Adds 7 to the first row
matrix[1].push_back(8);          // Adds 8 to the second row

1. Accessing the elements in the 2D vector: To access a specific element in the 2D vector, you need to specify the row and column index:

   int element = matrix[row_index][col_index];
   

2. Iterating over the 2D vector: You can use nested loops to iterate over the elements of the 2D vector:

   for (size_t i = 0; i < matrix.size(); i++) {
    for (size_t j = 0; j < matrix[i].size(); j++) {
        // Access and process the elements
        int element = matrix[i][j];
    }
   }
   

By following these steps, you can easily add elements to a 2D vector in C++. The flexibility of vectors allows you to dynamically resize and manipulate the 2D structure according to your needs.

#C++ #2DVector