Difference Between one-dimensional and two-dimensional array

Last Updated : 3 Oct, 2025

Array is a data structure that is used to store variables that are of similar data types at contiguous locations. The main advantage of the array is random access and cache friendliness. There are mainly three types of the array:

It is a list of the variable of similar data types.
It allows random access and all the elements can be accessed with the help of their index.
The size of the array is fixed.
For a dynamically sized array, vector can be used in C++.
Representation of 1D array:

Two Dimensional Array:

It is a list of lists of the variable of the same data type.
It also allows random access and all the elements can be accessed with the help of their index.
It can also be seen as a collection of 1D arrays. It is also known as the Matrix.
Its dimension can be increased from 2 to 3 and 4 so on.
They all are referred to as a multi-dimension array.
The most common multidimensional array is a 2D array.
Representation of 2 D array:

Difference Table:

Basis	One Dimension Array	Two Dimension Array
Definition	Store a single list of the element of a similar data type.	Store a 'list of lists' of the element of a similar data type.
Representation	Represent multiple data items as a list.	Represent multiple data items as a table consisting of rows and columns.
Declaration	The declaration varies for different programming language: For C++, datatype variable_name[row] For Java, datatype [] variable_name= new datatype[row]	The declaration varies for different programming language: For C++, datatype variable_name[row][column] For Java, datatype [][] variable_name= new datatype[row][column]
Dimension	One	Two
Size(bytes)	size of(datatype of the variable of the array) * size of the array	size of(datatype of the variable of the array)* the number of rows* the number of columns.
Address calculation.	Address of a[index] is equal to (base Address+ Size of each element of array * index).	Address of a[i][j] can be calculated in two ways row-major and column-major Column Major: Base Address + Size of each element (number of rows(j-lower bound of the column)+(i-lower bound of the rows)) Row Major: Base Address + Size of each element (number of columns(i-lower bound of the row)+(j-lower bound of the column))
Example	int arr[5]; //an array with one row and five columns will be created. {a , b , c , d , e}	int arr[2][5]; //an array with two rows and five columns will be created. a b c d e f g h i j

2D Arrays are used to implement matrices.
Arrays can be used to implement various data structures like a heap, stack, queue, etc.
They allow random access.
They are cache-friendly.

Comment

Article Tags:

URL: https://www.geeksforgeeks.org/dsa/difference-between-one-dimensional-and-two-dimensional-array/