How Can I Efficiently Create a Dynamic Two-Dimensional Array in C Based on User Input?

Creating a Dynamic Two-Dimensional Array Based on User Input

In some programming scenarios, it may be necessary to create a two-dimensional array with a size determined by user input. While traditional arrays require fixed dimensions at declaration, C provides solutions to tackle this issue.

Option 1: Using a Vector of Vectors

A vector of vectors, denoted as vector>, can be utilized to dynamically create a two-dimensional array. However, this method can be inefficient due to repeated pointer dereferences, leading to slower performance.

Option 2: Using a Custom Matrix Class with Overload Operator

A more efficient approach involves creating a custom matrix class that handles the memory allocation and provides an overloaded operator for accessing elements. This approach ensures efficient memory management and faster access times.

template <class T>
class matrix {
    int columns_;
    std::vector<T> data;

public:
    matrix(int columns, int rows) : columns_(columns), data(columns * rows) {}

    T &operator()(int column, int row) { return data[row * columns_ + column]; }
};

In this implementation, the matrix class maintains the column size and a single underlying vector for data storage. The overloaded operator() allows for convenient subscript-like syntax for accessing elements.

Example Usage:

matrix<int> myMatrix(5, 5); // Declare a 5x5 matrix

myMatrix(0, 0) = 10; // Set the (0, 0) element to 10
std::cout << myMatrix(0, 0); // Output the (0, 0) element, which should be 10

Conclusion

This article explored two options for creating dynamic two-dimensional arrays, providing a more detailed and performant alternative to the traditional vector of vectors approach. The custom matrix class with overloaded operator offers efficient memory management and improved access speed, making it a suitable choice for scenarios where performance is crucial.

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