Procedural Programming with C++ Explainer

How C++ Stores a 2D Array in Memory

A 2D array in C++ is really one long row in memory.

Lesson notes

Key points

Declaring int m[2][3]; creates two rows of three integers, accessed as m[row][column].
In memory, C++ uses row-major order: all of row zero is stored first, then row one.
The element m[i][j] sits at position i times the number of columns plus j from the start.
That is why a function parameter must state the column count, like int m[][3], so it can compute offsets.

Takeaway: 2D arrays are stored row by row; columns fix the layout.

Quick check: Why must int m[][3] keep the 3 in a parameter?

To compute element offsets
To limit the number of rows
To stop pass by value

2D arrayRow-major orderIndex formulaColumn size required

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