What are the differences between one-dimensional and two-dimensional arrays?

One-dimensional arrays store a linear series of elements, while two-dimensional arrays store elements in rows and columns, like a table.

A one-dimensional array is the simplest form of an array that stores a sequence of elements of the same type. Each element in the array can be accessed directly by its index. For example, if we have an array of integers, we can access the fifth element directly by using the index 4 (since array indices usually start at 0). This type of array is often used when you need to store and manipulate a list of items, such as a list of student names or a list of test scores.

On the other hand, a two-dimensional array is essentially an array of arrays. It stores elements in a tabular form, with rows and columns. Each element in the array can be accessed by using two indices: one for the row and one for the column. This type of array is often used when you need to store and manipulate data that naturally fits in a table, such as a matrix of numbers, a spreadsheet of data, or a chess board.

In terms of memory layout, elements in a one-dimensional array are stored in a contiguous block of memory. This makes accessing elements very efficient, as you can simply calculate the memory address of an element based on its index. However, this also means that the size of the array must be known in advance and cannot be changed once the array is created.

In contrast, a two-dimensional array can be thought of as an array of pointers to arrays. The outer array contains pointers to the inner arrays, which can be of different lengths. This allows for more flexibility in terms of the size and shape of the array, but it also makes accessing elements slightly more complex, as you need to follow two pointers to get to an element. Furthermore, the elements of a two-dimensional array are not guaranteed to be stored in a contiguous block of memory, which can impact performance if the array is large and the memory access pattern is not well-optimised.