2d vector c++ declaration

To declare a 2D vector in C++, you can follow these steps:

Step 1: Include the necessary header file for using the vector class. In this case, you need to include the <vector> header file.

Step 2: Declare a variable of type vector<vector<T>>, where T is the type of data you want to store in the 2D vector.

Step 3: Initialize the 2D vector by providing the dimensions and initial values (if any) using the constructor.

Here's an example of a 2D vector declaration in C++:

#include <vector>

int main() {
    // Step 1: Include the necessary header file

    // Step 2: Declare a variable of type vector<vector<T>>
    std::vector<std::vector<int>> my2DVector;

    // Step 3: Initialize the 2D vector with dimensions and initial values
    int numRows = 3;
    int numCols = 4;
    int initialValue = 0;
    my2DVector.assign(numRows, std::vector<int>(numCols, initialValue));

    return 0;
}

In the above example, we have declared a 2D vector my2DVector of type vector<vector<int>>. We have initialized it with a size of 3 rows and 4 columns, with each element initialized to 0.

You can modify the type T and the dimensions according to your requirements.