We’ll discuss two-dimensional array. Array-2D, also known as an array of arrays, deals with the matrix related program. Let us begin with a simple example of initializing and displaying a matrix.
Initialization of Array-2D
We can initialize 2-D array using both run and compile time initialization.
Run time initialization
Let us try the problem mentioned above using run-time initialization.
#include<stdio.h>
int main()
{
/* array declaration-2D*/
int a[10][10];
int i, j,m,n;
printf("enter row and column size:\n");
scanf("%d%d",&m,&n);
printf("enter %d*%d order matrix a[][]:\n",m,n);
for(i=0; i<m; i++)
{
for(j=0;j<n;j++)
{
scanf("%d", &a[i][j]);
}
}
printf("%d*%d order matrix a[][] is\n:", m, n);
for(i=0; i<m; i++)
{
for(j=0;j<n;j++)
{
printf("%d\t",a[i][j]);
} printf("\n");
}
return 0;
}
Few points are to be remembered to initialize an array.
- int a[5][ ]; this type of array declaration is invalid as the second dimension i.e. no. of column must be identified.
- int a[ ][ ] ; this is also invalid. At least one dimension i.e.column must be declared.
- int a[3][3]; this is valid declaration.
- int a[ ][ 3]; this is also a valid declaration.
Compile-time Initialization
#include<stdio.h>
int main()
{
int a[3][3]={ {4, 2, 1}, {3, 5, 9}, {6, 8, 7} };
int i,j;
for(i=0; i<3; i++)
{
for(j=0;j<3;j++)
{
scanf("%d",&a[i][j]);
}
}
printf("matrix is:\n");
for(i=0; i<3; i++)
{
for(j=0;j<3;j++)
{
printf("%d\t",a[i][j]);
}
printf("\n");
}
return 0;
}
We’ll try few more examples regarding matrix addition and subtraction.
Program to read two m*n order matrix and perform matrix addition and matrix subtraction.
#include<stdio.h>
int main()
{
int a[10][10],b[10][10],i,j,m,n,c[10][10];
printf("enter the row and column size of matrix :\n"); scanf("%d%d",&m,&n);
printf("enter %d*%d order matrix a[i][j]:\n",m,n);
for(i=0;i<=m-1;i++)
{
for (j=0;j<=n-1;j++)
{
scanf("%d",&a[i][j]);
}
}
printf("the matrix a[] is:\n");
for(i=0;i<=m-1;i++)
{
for (j=0;j<=n-1;j++)
{
printf("%d\t",a[i][j]);
}
printf("\n");
}
printf("enter %d*%d order matrix b[][]:\n",m,n);
for(i=0;i<=m-1;i++)
{
for (j=0;j<=n-1;j++)
{
scanf("%d",&b[i][j]);
}
}
printf("the matrix b[] is:\n");
for(i=0;i<=m-1;i++)
{
for (j=0;j<=n-1;j++)
{
printf("%d\t",b[i][j]);
}
printf("\n");
}
printf("the resultant matrix after addition is:\n");
for(i=0;i<=m-1;i++)
{
for (j=0;j<=n-1;j++)
{
c[i][j]=a[i][j]+b[i][j];
printf("%d\t",c[i][j]);
}
printf("\n");
}
printf("\nthe resultant matrix after subtraction is:\n");
for(i=0;i<=m-1;i++)
{
for (j=0;j<=n-1;j++)
{
c[i][j]=a[i][j]-b[i][j];
printf("%d\t",c[i][j]);
}
printf("\n");
}
return 0;
}
Program to find the transpose of matrix.
#include<stdio.h>
int main()
{
int a[3][3]={ {4, 2, 1}, {3, 5, 9}, {6, 8, 7} };
int i,j;
for(i=0; i<3; i++)
{
for(j=0;j<3;j++)
{
scanf("%d",&a[i][j]);
}
}
printf("matrix is:\n");
for(i=0; i<3; i++)
{
for(j=0;j<3;j++)
{
printf("%d\t",a[i][j]);
}
printf("\n");
}
printf("the transpose of matrix is:\n");
for(i=0; i<3; i++)
{
for(j=0;j<3;j++)
{
printf("%d\t",a[j][i]);
}
printf("\n");
}
return 0;
}
Program to perform matrix multiplication.
#include<stdio.h>
int main()
{
int a[10][10],b[10][10],c[10][10],r1,r2,c1,c2,i,j,k;
printf("enter the row an column size of matrix a[10][10]:\n");
scanf("%d%d",&r1,&c1);
printf("enter the row an column size of matrix b[10][10]:\n");
scanf("%d%d",&r2,&c2);
if(c1!=r2)
printf("matrix multiplication is not possible");
else
{
printf("enter %d*%d order matrix a[10][10]:\n",r1,c1);
for(i=0;i<r1;i++)
{
for(j=0;j<c1;j++)
{
scanf("%d",&a[i][j]);
}
}
printf("the first matrix is:\n");
for(i=0;i<r1;i++)
{
for(j=0;j<c1;j++)
{
printf("%d\t",a[i][j]);
}
printf("\n");
}
printf("enter %d*%d order matrix b[10][10]:\n",r2,c2);
for(i=0;i<r2;i++)
{
for(j=0;j<c2;j++)
{
scanf("%d",&b[i][j]);
}
}
printf("the second matrix is:\n");
for(i=0;i<r2;i++)
{
for(j=0;j<c2;j++)
{
printf("%d\t",b[i][j]);
}
printf("\n");
}
for(i=0;i<r1;i++)
{
for(j=0;j<c2;j++)
{
c[i][j]=0;
for(k=0;k<c1;k++)
{
c[i][j]+=a[i][k]*b[k][j];
}
}
}
printf("resultant matrix after multiplication is:\n");
{
for(i=0;i<r1;i++)
{
for(j=0;j<c1;j++)
{
printf("%d\t",c[i][j]);
}
printf("\n");
}
}
}
return 0;
}
