In this program, we are going to make a program for subtraction of two matrices in c++. To make this program, we initialize three matrices A, B & C then we insert elements of matrices A & B by the user using nested for loops. At last, we subtract the corresponding elements of matrices A & B and then we store those values in another matrix C and display all elements of matrix C.

Subtraction of two matrices in c++ using 2d arrays

#include <iostream>
using namespace std;
int main()
{

    int r, c;
    cout << "\n Enter number of rows:";
    cin >> r;
    cout << "\n Enter number of columns:";
    cin >> c;
    cout << "\n Enter elements of Matrix A:\n";
    int A[r][c], B[r][c], C[r][c];
    for (int i = 0; i < r; i++)
    {
        for (int j = 0; j < c; j++)
            cin >> A[i][j];
    }
    cout << "\n Matrix A:\n";
    for (int i = 0; i < r; i++)
    {
        for (int j = 0; j < c; j++)
        {
            cout << A[i][j];
            cout << "\t";
        }
        cout << "\n";
    }
    cout << "\n Enter elements of Matrix B:\n";
    for (int i = 0; i < r; i++)
    {
        for (int j = 0; j < c; j++)
        {
            cin >> B[i][j];
        }
    }
    cout << "\n Matrix B:\n";
    for (int i = 0; i < r; i++)
    {
        for (int j = 0; j < c; j++)
        {
            cout << B[i][j];
            cout << "\t";
        }
        cout << "\n";
    }
    cout << "\n Subtraction of Matrix B from A:\n";
    for (int i = 0; i < r; i++)
    {
        for (int j = 0; j < c; j++)
        {
            C[i][j] = A[i][j] - B[i][j];
            cout << C[i][j];
            cout << "\t";
        }
        cout << "\n";
    }
    return 0;
}

Approach to make a program for Subtraction of two matrices in c++:

  • First, we initialize three matrices A, B and C using 2D arrays.
  • We take the number of rows and columns of both matrices A and B.
  • We insert elements of matrices A by user using nested for loops.
  • We print elements of matrices A on the output screen using nested for loop.
  • We insert elements of matrices B by user using nested for loops.
  • We print elements of matrices B on the output screen using nested for loop.
  • Using nested for loop, we subtract the corresponding elements of matrices A & B and stores these values in matrix C.
  • We print all the elements of matrix C which contains the subtraction of corresponding elements of matrices A & B.

Subtract two matrices using vectors

To subtract two matrices in C++, you can follow these steps:

  1. Create two 2d vectors of the same size.
  2. Iterate over the matrices using nested for loops. The outer loop will iterate over the rows and the inner loop will iterate over the columns.
  3. At each iteration, subtract the elements of the second matrix from the corresponding elements of the first matrix and store the result in a new matrix.
  4. Return the new matrix as the result of the subtraction.

Here is an example of how you might implement this in C++:

#include <iostream>
#include <vector>
using namespace std;

// Function to subtract two matrices
vector<vector<int>> subtract(vector<vector<int>> &num1, vector<vector<int>> &num2)
{

    // Subtract the matrices
    int rows = num1.size(), cols = num1[0].size();
    vector<vector<int>> res(rows, vector<int>(cols, 0));
    for (int i = 0; i < rows; i++)
    {
        for (int j = 0; j < cols; j++)
            res[i][j] = num1[i][j] - num2[i][j];
    }

    return res;
}

int main()
{
    int rows, cols;
    cin >> rows >> cols;

    vector<vector<int>> num1(rows, vector<int>(cols, 0));
    vector<vector<int>> num2(rows, vector<int>(cols, 0));

    cout<<"Enter elements of 1st Matrix: ";
    for (int i = 0; i < rows; i++)
    {
        for (int j = 0; j < cols; j++)
        {
            cin >> num1[i][j];
        }
    }

    cout<<"Enter elements of 2nd Matrix: ";
    for (int i = 0; i < rows; i++)
    {
        for (int j = 0; j < cols; j++)
        {
            cin >> num2[i][j];
        }
    }

    vector<vector<int>> ans = subtract(num1, num2);

    // print the resultant matrix
    for (auto i : ans)
    {
        for (auto j : i)
        {
            cout << j << " ";
        }
        cout << endl;
    }

    return 0;
}

Questions and Answers:

How do you subtract two matrices in C++?

Using nested for loop, we subtract the corresponding elements of two matrices and store these values in another matrix.

How do you display a matrix in C++? 

 We display a matrix using nested for loop statement
for (int i = 0; i < r; i++)
    {
        for (int j = 0; j < c; j++)
        {
            cout << A[i][j];
            cout << "\t";
        }
        cout << "\n";
    }
Where r is the number of rows of matrices A & B and c is the number of columns of matrices A & B

What is the value of the identity matrix?

It is a square matrix, whose all the diagonal elements are 1 and all the non-diagonal elements are 0.
For example, An identity matrix of order 3*3
1         0         0
0         1         0
0         0         1

Thanks for reading this program for the Subtraction of two matrices in c++. I hope you enjoy this program as much as I enjoy offering this to you. If you have any questions or queries related to this program, please don’t hesitate to comment below or contact me.

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