C programming language supports multi dimensional Arrays.

- Multi dimensional arrays have more than one subscript variables.
- Multi dimensional array is also called as matrix.
- Multi dimensional arrays are array of arrays.

## Declaration of Multi Dimensional Array

*data_type array_name[size1][size2]...[sizeN];*Above statement will declare an array of N dimensions of name array_name, where each element of array is of type data_type. The maximum number of elements that can be stored in a multi dimensional array array_name is size1 X size2 X size3...sixeN.

*For Example:*

**Declaration of two dimensional integer array**

int board[8][8];

**Declaration of three dimensional character array**

char cube[50][60][30];

## Two Dimensional Array in C

Two dimensional arrays are most common type of multi dimensional array. A **two dimensional array** in C language is represented in the form 2D matrix having rows and columns.

- A two dimensional matrix is an array of one dimensional arrays.
- Two dimensional array requires two subscript variables or indexes.
- One subscript represents the row index while other represent column index of an element in matrix.
- Elements of a two dimensional array are stored in contiguous memory location. First all elements of first row are store then all elements of second row and so on.

Any element in **two dimensional matrix** is uniquely identified by array_name[row_Index][column_Index], where row_index and column_index are the subscripts that uniquely specifies the position of an element in a **2D matrix**.

An element in second row and third column of an two dimensional matrix whose name is board is accessed by board[1][2].

Like single dimensional array, indexing starts from 0 instead of 1.

We can declare a two dimensional matrix of R rows and C columns as follows:

data_type array_name[R][C];

*For Example:*

A two dimensional integer matrix of 3 rows and 3 columns can be declared as

int score[3][3];

## Initialization of Two Dimensional Array

Two dimensional arrays can be initialized by specifying elements for each row inside curly braces. The following declaration initializes a two dimensional matrix of 4 rows and 3 columns.

int matrix[4][3] = { {1, 2, 3}, /* Initialization of first row */ {4, 5, 6}, /* Initialization of second row */ {7, 8, 9}, /* Initialization of third row */ {10, 11, 12}, /* Initialization of fourth row */ };Similarly, we can initialize any multi dimensional array.

A two dimensional matrix can be initialized without using any internal curly braces as follows:

int matrix[4][3] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};

In above declaration, compiler will assign first four values(1, 2, 3 and 4) to first row of matrix and within a row it will populate elements from left to right. Then next four elements to second row and so on.

## C program to find sum of all elements of two dimensional array

#include <stdio.h> int main(){ /* Two dimentional array declaration */ int matrix[20][20]; int rowCounter, colCounter, rows, cols, sum=0; printf("Enter size of a matrix\n"); scanf("%d %d", &rows, &cols); /* Populating elements inside matrix */ printf("Enter elements of a matrix of size %dX%d\n", rows, cols); for(rowCounter = 0; rowCounter < rows; rowCounter++){ for(colCounter = 0; colCounter < cols; colCounter++){ scanf("%d", &matrix[rowCounter][colCounter]); } } /* Accessing all elements of matrix to calculate their sum */ for(rowCounter = 0; rowCounter < rows; rowCounter++){ for(colCounter = 0; colCounter < cols; colCounter++){ sum += matrix[rowCounter][colCounter]; } } printf("Sum of all elements = %d", sum); return 0; }Above program first declares a matrix of size 20X20 then populates it by taking input form user. Now using two for loops it access each element of matrix and add their values to a variable sum.

Output

Enter size of a matrix 3 3 Enter elements of a matrix of size 3X3 1 2 3 4 5 6 7 8 9 Sum of all elements = 45