How do I implement 2D vectors in C++17?

How do I implement 2D vectors in C++17?

You can implement 2D vectors in C++17 using a vector of vectors. Here's a simple example:

#include <iostream>
#include <vector>

int main() {
    int rows = 3, cols = 4;
    std::vector<std::vector<int>> vec(rows, std::vector<int>(cols, 0));

    // Accessing elements
    vec[1][2] = 5;
    std::cout << "Element at (1, 2): " << vec[1][2] << std::endl;
    return 0;
}

What if I want to initialize it with specific values?

You can initialize a 2D vector with specific values by providing a nested initializer list. For example:

std::vector<std::vector<int>> vec = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};

How can I iterate through the elements of a 2D vector?

You can use nested loops to iterate through a 2D vector. Here's an example:

for (const auto& row : vec) {
    for (const auto& elem : row) {
        std::cout << elem << " ";
    }
    std::cout << std::endl;
}

Are there any performance considerations I should be aware of?

Yes, using a vector of vectors can lead to non-contiguous memory allocation, which may affect performance. For better performance, consider using a single vector and calculating indices manually.