What are the rules for defining a two-dimensional array in C++?

In C++, the rule for defining a two-dimensional array is to use two square brackets in the array declaration. The first bracket represents the number of rows in the two-dimensional array, while the second bracket represents the number of columns. For example, the following is a definition of a 3×4 two-dimensional array:

int arr[3][4];

This will create a 2D array of integer type with 3 rows and 4 columns. Elements in the 2D array can be accessed using indexes, for example, arr[0][1] represents the element in the first row and second column.

Note that in C++, two-dimensional arrays are allocated as a continuous block of memory, with rows and columns closely arranged.