Question

In C++

Design a class to perform various matrix operations. A matrix is a set of numbers arranged in rows and columns. Therefore, every element of a matrix has a row position and a column position. If A is a matrix of five rows and six columns, we say that the matrix A is of the size 5 X 6 and sometimes denote it as Asxc. Clearly, a convenient place to store a matrix is in a two-dimensional array. Two matrices can be added and subtracted if they have the same size. Suppose A = [ay] and B = [bi] are two matrices of the size m X n, in which ai denotes the element of A in the ith row and the ſth column, and so on. The sum and difference of A and B are given by: A + B = [aj + bij] A - B = [ai - bi] The multiplication of A and B (A + B) is defined only if the number of columns of A is the same as the number of rows of B. If A is of the size m X n and B is of the size n X t, then A + B = [C;] is of the size m X t and the element c., is given by the formula: Cik = a; but + aizb2k + ... + ainbenk Design and implement a class matrixType that can store a matrix of any size. Overload the operators +, -, and * to perform the addition, subtraction, and multiplication operations, respectively, and overload the operator << to output a matrix. Also, write a test program to test various operations on the matrices.

Answer 1

Here is the solution if you have any doubts then you can write in the comment section.

Please give feedback.

Solution: In the solution if matrix are not in the form required for particular operation then it will return matrix with row = 0 and column = 0 as a result, and print a error message.

other solution may be that check condition before calling any method.

#include <bits/stdc++.h>
using namespace std;
//class MatrixType
class MatrixType
{
    //variables
    public:
    int rows;
    int columns;
    int **matrix;
    //constructor
    MatrixType(int row,int column )
    {
        //set rows and columns
        rows=row; 
        columns=column;
        //define and initialize array
        matrix=new int* [columns];
        
        for(int i =0;i<rows;i++)
        {
            matrix[i]=new int[columns];
        }
        for(int i=0;i<rows;i++)
            for(int j=0;j<columns;j++)
                matrix[i][j]=0;            
    }
    //overloding + operator
    MatrixType operator +(MatrixType other) 
    {
        /*if matrix two matrix have different rows or different columns then 
        return same matrix*/
        if (rows!=other.rows ||columns!=other.columns)
        {
            //create new object of MatrixType
            MatrixType temp(0,0);  
            cout<<"Matrix can't be added!\n";
            return temp;
        }
        //otherwise add 2 matrix
        else
        {   //create new object of MatrixType
            MatrixType temp(rows,columns);   
            for(int i=0;i<rows;i++)
                for(int j=0;j<columns;j++)
                    temp.matrix[i][j]+=other.matrix[i][j]+matrix[i][j];
        
            //return MatrixType object
            return temp;
        }
     
    }
    //overloding - operator
    MatrixType operator -(MatrixType other) 
    {
         
        /*if matrix two matrix have different rows or different columns then 
        return same matrix*/
        if (rows!=other.rows ||columns!=other.columns)
        {
            //create new object of MatrixType
            MatrixType temp(0,0);  
            cout<<"Matrix can't be subtracted!\n";
            return temp;
        }
        //otherwise subtract matrix
        else
        {
            //create MatrixType object
            MatrixType temp(rows,columns); 
            for(int i=0;i<rows;i++)
                for(int j=0;j<columns;j++)
                    temp.matrix[i][j]+=(matrix[i][j]-other.matrix[i][j]);
        
            //return MatrixType object
            return temp;
        }
     
    }

    //overloding * operator
    MatrixType operator *(MatrixType other)   
    {
        /*if columns of 1st matrix not equal to rows of 2nd matrix then return
        1st matrix because multiplication can't take place*/
        if (columns!=other.rows)
        {
            MatrixType temp(0,0);
            cout<<"Matrix can't be multiplied!\n";
            return temp;
        }
        //otherwise calculate multiplication
        else
        {
            //create object of MatrixType
            MatrixType temp(rows,other.columns);  
            for(int i=0;i<rows;i++)
                for(int j=0;j<other.columns;j++)
                    for(int k =0;k<columns;k++)
                        temp.matrix[i][j]+=(matrix[i][k]*other.matrix[k][j]);
            return temp;          
        }

    }
    //overloding << operator
    friend ostream& operator<<(ostream& output, MatrixType& m)
    {
        if(m.rows!=0&&m.columns!=0)
        for(int i=0;i<m.rows;i++)
        {   for(int j=0;j<m.columns;j++)
                output<<m.matrix[i][j]<<" ";
            cout<<"\n";
        } 
        return output;  
    }
    
};
//main() for testing
int main()
{
    //variables
    int row,column;
    //read row and column from user
    cout<<"Enter row and column of matrix: ";
    cin>>row>>column;
    //create object of MatrixType
    MatrixType m1(row,column);
    cout<<"Enter matrix\n";
    //read element of matrix
    for(int i=0;i<row;i++)
    {
        for(int j=0;j<column;j++)
        {
            cin>>m1.matrix[i][j];
        }
    }
    
    //read row and column from user
    cout<<"Enter row and column of matrix 2: ";
    cin>>row>>column;
    //create object of MatrixType
    MatrixType m2(row,column);
    cout<<"Enter matrix\n";
    //read element of matrix
    for(int i=0;i<row;i++)
    {
        for(int j=0;j<column;j++)
        {
            cin>>m2.matrix[i][j];
        }
    }
    
    //performing various operation
    MatrixType m3=m1+m2;
    MatrixType m4=m1-m2;
    MatrixType m5=m1*m2;
    
    //print matrix
    cout<<"\nMatrix 1\n"<<m1;
    cout<<"\nMatrix 2\n"<<m2;
    cout<<"\nMatrix 3\n"<<m3;
    cout<<"\nMatrix 4\n"<<m4;
    cout<<"\nMatrix 5\n"<<m5;
    

    return 0;
}

Output:

input Enter row and column of matrix: 22 Enter matrix 58 38 Enter row and column of matrix 2: 2 2 Enter matrix 38 89 Matrix 1 58 38 Matrix 2 38 8 9 Matrix 3 8 16 11 17 Matrix 4 20 -5 -1 Matrix 5 79 112

Matrix 4 20 -5 -1 Matrix 5 79 112 73 96 ... Program finished with exit code 0 Press ENTER to exit console.

Thank You!