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Matrix_multiplication.cpp

#include <iostream>
#include <ctime>
#include <fstream>
using namespace std;

void FillMatrix(int **matrix, const int rows, const int cols){
    for (int i=0; i<rows; i++){
        for (int j=0; j<cols; j++){
            matrix[i][j]=rand()%15;
        }
    }
}

void PrintMatrix(int **matrix, const int rows, const int cols){
    for (int i=0; i<rows; i++){
        for (int j=0; j<cols; j++){
            cout << matrix[i][j] << "\t";
        }
        cout << endl;
    }
}


int main(){
    srand(time(NULL));

    int cols_a;
    int rows_a;
    int cols_b;
    int rows_b;

    again:

    cout << "Число строк матрицы А" << endl;
    cin >> rows_a;
    cout << "Число столбцов матрицы А" << endl;
    cin >> cols_a;
    cout << "Число строк матрицы В" << endl;
    cin >> rows_b;
    cout << "Число столбцов матрицы В" << endl;
    cin >> cols_b;

    if (cols_a==rows_b) {
        int **matrix_c = new int *[rows_a];
        for (int i = 0; i < rows_a; i++){
            matrix_c[i] = new int [cols_b];
        }

        int **matrix_a = new int *[rows_a];
        for (int i = 0; i < rows_a; i++){
            matrix_a[i] = new int[cols_a];
        }

        int **matrix_b = new int *[rows_b];
        for (int i = 0; i < rows_b; i++){
            matrix_b[i] = new int [cols_b];
        }

        FillMatrix(matrix_a, rows_a, cols_a);
        FillMatrix(matrix_b, rows_b, cols_b);
        for (int i = 0; i < rows_a; i++){
            for (int k = 0; k < cols_b; k++){
                for (int j = 0; j < cols_a; j++){
                    matrix_c[i][k] += matrix_a[i][j] * matrix_b[j][k];
                }
            }
        }

        cout << "Matrix A" << endl;
        PrintMatrix(matrix_a, rows_a, cols_a);
        cout << endl << "Matrix B" << endl;
        PrintMatrix(matrix_b, rows_b, cols_b);
        cout << endl << "Matrix C" << endl;
        PrintMatrix(matrix_c, rows_a, cols_b);

        ofstream txt_matrix;{
        txt_matrix.open("matrix.txt");
        txt_matrix << "Matrix A" << endl;
        for (int i=0; i<rows_a; i++){
            for (int j=0; j<cols_a; j++){
                txt_matrix << matrix_a[i][j] << "\t";
            }
            txt_matrix << endl;
        }

        txt_matrix << endl << "Matrix B" << endl;
        for (int i=0; i<rows_b; i++){
            for (int j=0; j<cols_b; j++){
                txt_matrix << matrix_b[i][j] << "\t";
            }
            txt_matrix << endl;
        }

        txt_matrix << endl << "Matrix C" << endl;
        for (int i=0; i<rows_a; i++){
            for (int j=0; j<cols_b; j++){
                txt_matrix << matrix_c[i][j] << "\t";
            }
            txt_matrix << endl;
        }
        txt_matrix.close();}
    }
    else{
        cout << endl << "Число столбцов матрицы А должно быть равным числу строк матрицы В!" << endl;
        goto again;
    }
}