Multi-dimensional arrays

                Multi-dimensional arrays are those which have more than one dimensions. Multi-dimensional arrays are defined in much the same manner as one dimensional array, except that a separate pair of square brackets is required for each subscript. Thus, two dimensional arrays will require two pairs of square brackets; three dimensional arrays will require three pairs of square brackets and so on. The two dimensional array is also called matrix. Multi-dimensional array can be defined as following

  storage_class  data_type  array_name[expression1] [expression2] ...[expression n];

                  Here, expression1, expression2…..expression n are positive valued integer expressions that indicate the number of array elements associated with each subscript. An m*n two dimensional array can be thought as tables of values having m rows and n columns.

 An example

 int X[3][3] can be shown as follows

	Col 1	Col 2	Col 3
Row 1	X[0][0]	X[0][1]	X[0][2]
Row 2	X[1][0]	X[1][1]	X[1][2]
Row 3	X[2][0]	X[2][1]	X[2][2]

Initialization of multi-dimensional array:

         Like one dimensional array, multi-dimensional arrays can be initialized at the time of array definition or declaration. A few example of 2-D array initialization are:

int marks[2][3]={   {2, 4, 6},                                    {8, 10, 12}                                 };       int marks1[][3]={   {2, 4, 6},                                    {8, 10, 12}                                 };    int marks2[2][3]={ 2,4,6,8, 10, 12};    int marks3[ ][3]={ 2,4,6,8, 10, 12};    int marks4[ ][3]={ 2,4,6,8, 10};     What is the value of marks4[1][2]?

 

    

All above examples are valid. While initializing an array, it is necessary to mention the second dimension (column) whereas the first dimension (row) is optional.

   Thus, following are invalid

       int marks3[3][]={ 2,4,6,8, 10, 12};

       int marks4[][]={ 2,4,6,8, 10};    /* error!!!*/

Example: Write a program to read two 3*3 matrixes and display their sum.

#include<stdio.h> #include<conio.h> void main()   {   int a[3][3],b[3][3],sum[3][3],i,j;   clrscr();   printf("Enter First matrix row by row\n");   for(i=0;i<3;i++)      for(j=0;j<3;j++)        scanf("%d",&a[i][j]);   printf("Enter second matrix as first\n");   for(i=0;i<3;i++)      for(j=0;j<3;j++)       scanf("%d",&b[i][j]);    for(i=0;i<3;i++)    {  for(j=0;j<3;j++)       { sum[i][j]=a[i][j]+b[i][j];}     printf("\nThe sum matrix is:\n");}     for(i=0;i<3;i++)       {        for(j=0;j<3;j++)          {           printf("\t%d",sum[i][j]);           }           printf("\n");          }     getch();   }