2D Arrays in C++: Declare, Initialize & Operations

Key takeaways:

• A 2D array organizes data in a grid-like structure, which you typically process using nested for loops for rows and columns.
• When passing a static 2D array to a function, you must always specify the array’s column size in the function’s parameters.
• Static arrays have dimensions fixed at compile time, while dynamic arrays are created at runtime using new[] for variable sizing.
• You must manually deallocate dynamic arrays to prevent memory leaks by deleting each row and then the main pointer.
• For modern C++, std::vector<std::vector<int>> is the recommended alternative because it automatically manages memory and is safer to use.
• C++ stores 2D arrays in row-major order, so processing data row-by-row makes the best use of the CPU cache and runs faster on large datasets.
• A comparison of static arrays, pointer-based arrays, and vectors helps you pick the right structure for compile-time versus runtime sizing.
• std::vector supports range-based for loops, resizing, and jagged (uneven) rows, which raw arrays cannot do.
• std::mdspan, introduced in C++23, gives you a lightweight, multidimensional view over an existing contiguous buffer.

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