Program to create a square matrix and find the sum of diagonal elements

#include<iostream.h>
#include<conio.h>
void main()
{
clrscr();
int a[20][20],sum=0,m,n,i,j;
cout<<"Enter the size : ";
cin>>m>>n;
if(m==n)
{
cout<<"Enter the elements : ";
for(i=0;i<m;i++)
for(j=0;j<n;j++)
cin>>a[i][j];
for(i=0;i<m;i++)
{
for(j=0;j<m;j++)
{
if(i==j)
sum+=a[i][j];
}
}
cout<<sum;
}
else
cout<<"Not a square matrix";
getch();
}

Program for multiplication of matrix using " class "

To know about 'class' click here


#include<iostream.h>
#include<conio.h>
class matrix
 {
 int a[10][10];
 int m,n;
 public:
 void input();
 void output();
 void multiply(matrix,matrix);
 };
 void matrix::input()
 {
 cout<<"Enter the number of row : ";
 cin>>m;
 cout<<"Enter the number of column : ";
 cin>>n;
 cout<<"Matrix"<<"\n";
 for(int i=0;i<m;i++)
 {
 for(int j=0;j<n;j++)
 {
 cin>>a[i][j];
 }
 }
 }
 void matrix :: output()
 {
 for(int i=0;i<m;i++)
 {
 cout<<"\n";
 for(int j=0;j<n;j++)
 {
 cout<<a[i][j]<<"\t";
 }
 }
 }
 void matrix :: multiply(matrix m1, matrix m2)
 {
 if(m1.n!=m2.m)
    {
     cout<<"matrix multiplication is not possible";
    }
 else
    {
     for(int i=0;i<m1.m;i++)
    {
     for(int j=0;j<m2.n;j++)
    {
     a[i][j]=0;
     for(int k=0;k<m1.n;k++)
     {
     a[i][j]=a[i][j] +( m1.a[i][k]*m2.a[k][j]);
     m=m1.m;
     n=m2.n;
    }
 }
 }
 }
 }
 void main()
 {
 clrscr();
 matrix m1,m2,m3;
 m1.input();
 m2.input();
 m3.multiply(m1,m2);
 m3.output();
 getch();
 }

Program to find out the sum of two matrices

#include<iostream.h>
#include<conio.h>
void main()
{
int a[10][10],b[10][10],c[10][10],i,j,m,n;
clrscr();
cout<<"Enter the number of raws and columns of two matrices : ";
cin>>m>>n;
cout<<"Enter the elements into matrix A\n";
for(i=0;i<m;i++)
for(j=0;j<n;j++)
cin>>a[i][j];
cout<<"\nEnter the elements into matrix B\n";
for(i=0;i<m;i++)
for(j=0;j<n;j++)
cin>>b[i][j];
for(i=0;i<m;i++)
for(j=0;j<n;j++)
c[i][j]=a[i][j]+b[i][j];
for(i=0;i<m;i++)
    {
    cout<<"\n";
    for(j=0;j<n;j++)
    cout<<c[i][j];
    cout<<"\t";
    }
getch();
}

Program to find the sum of all the elements of a matrix

#include<iostream.h>
#include<conio.h>
void main()
{
 clrscr();
 int a[20][20],sum=0,m,n,i,j;
 cout<<"Enter the size of matrix : "
 cin>>m>>n;
 cout<<"Enter the elements : ";
 for(i=0;i<m;i++)
 for(j=0;j<n;j++)
 {
     cin>>a[i][j];
     sum+=a[i][j];
 }
 cout<<"Sum of elements of the matrix is : "<<sum
 getch();
}

Program to access the elements in two dimensional array and display it

#include<iostream.h>
#include<conio.h>
void main()
{
 clrscr();
 int a[20][20],m,n,i,j;
 cout<<"Enter the size of matrix : "
 cin>>m>>n;
 cout<<"Enter the elements : ";
 for(i=0;i<m;i++)
 for(j=0;j<n;j++)
 cin>>a[i][j];
 cout<<"The matix is : "<<"\n";
 for(i=0;i<m;i++)
 {
 for(j=0;j<n;j++)
 {
 cout<<a[i][j]<<"\t";
 }
 }
 getch();
}