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>
#include <conio.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);
getch();
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