28_09_multiply_matrix

#include <iostream>
#include <ctime>

#define My_VAl1 "Hello world!"
#define My_VAl2 "Hello world!"
#define My_VAl3 {1, 2, 4, 5}   // это плохая практика

using namespace std;


inline int get_rand(int min, int max) { // inline - для вставки команд функции в место вызова
    if (min > max)
        swap(min, max);
    return min + rand() % (max - min + 1);
}

void create(int** &matr1, int size1, int size2) {
    matr1 = new int* [size1];
    for (int k = 0; k < size1; ++k) {
        matr1[k] = new int[size2];
    }

    for (int k = 0; k < size1; ++k) {
        for (int n = 0; n < size2; ++n)
            //  matr1[k][n] = -10 + rand()%21 ; // так нормально
            matr1[k][n] = get_rand(0, 9); // так лучше
    }
}

void show(int**& matr1) {
    int size1 = _msize(matr1) / sizeof(matr1[0]);
    int size2 = _msize(matr1[0]) / sizeof(matr1[0][0]);
    for (int k = 0; k < size1; ++k) {
        for (int n = 0; n < size2; ++n)
            cout << matr1[k][n] << "\t";
        cout << endl;
    }
    cout << endl;
}

void transpose(int**& matr1) {
    int size1 = _msize(matr1) / sizeof(matr1[0]);
    int size2 = _msize(matr1[0]) / sizeof(matr1[0][0]);
    int** buff;
    create(buff, size2, size1);
    for (int k = 0; k < size1; ++k) {
        for (int n = 0; n < size2; ++n)
            buff[n][k] = matr1[k][n];
    }
    free(matr1);
    matr1 = buff;
}

// только квадратные матрицы
int** mult(int** matr1, int** matr2) {
    int size1 = _msize(matr1) / sizeof(matr1[0]);
    int size2 = _msize(matr1[0]) / sizeof(matr1[0][0]);
    int** res;
    create(res, size1, size2);
    // правильлное суммирование
    for(int k = 0; k < size1; ++k){
        for (int n = 0; n < size2; ++n) {
            res[k][n] = 0;
            for (int m = 0; m < size1; ++m) {
                res[k][n] += matr1[k][m] * matr2[m][n];
            }
        }
    }
    return res;
}


void free(int** &matr1) {
    int size1 = _msize(matr1) / sizeof(matr1[0]);
    for (int k = 0; k < size1; ++k) {
        delete[] matr1[k];
    }
    delete[] matr1;
}

void matrix_calculation() {
    srand(time(NULL));
    int** arr;
    int** arr1;
    /*
    cout << My_VAl1 << endl;
    int arr2[]My_VAl3;
    */

    create(arr, 3, 3);
    create(arr1, 3, 3);

    show(arr);
    show(arr1);

    int** multarr = mult(arr, arr1);
    show(multarr);
    free(multarr);
    /*
    show(arr);
    transpose(arr);
    transpose(arr);
    show(arr);
    */
    free(arr);
    free(arr1);
}

void show(int* arr) {
    int size1 = _msize(arr) / sizeof(arr[0]);
    for (int k = 0; k < size1; k++) {
        cout << arr[k] << " ";
    }
    cout << endl;
}

void add(int* &arr, int val) {
    int size1 = _msize(arr) / sizeof(arr[0]);
    int* buff = new int[size1 + 1];
    for (int k = 0; k < size1; k++) {
        buff[k] = arr[k];
    }
    buff[size1] = val;
    delete[] arr;
    arr = buff;
}

void add(int*& arr, int val, int id) {
    int size1 = _msize(arr) / sizeof(arr[0]);
    if ((id > 0) && (id < size1)) {
        int* buff = new int[size1 + 1];
        for (int k = 0; k < id; ++k) {
            buff[k] = arr[k];
        }
        buff[id] = val;
        for (int k = id; k < size1; ++k) {
            buff[k + 1] = arr[k];
        }
        delete[] arr;
        arr = buff;
    }
}

void remove(int*& arr, int id) {
    int size1 = _msize(arr) / sizeof(arr[0]);
    if ((id > 0) && (id < size1)) {
        int* buff = new int[size1 - 1];
        for (int k = 0; k < id; ++k)
            buff[k] = arr[k];
        for (int k = id + 1; k < size1; ++k)
            buff[k - 1] = arr[k];
        delete[] arr;
        arr = buff;
    }
}

void main() {
    int* arr = new int[0] {};
    show(arr);
    //arr[5] = 7;
    add(arr, 1);
    add(arr, 2);
    add(arr, 3);
    add(arr, 4);
    add(arr, 5);
    show(arr);
    add(arr, 77, 2);
    show(arr);
    remove(arr, 0);
    remove(arr, 0);
    show(arr);
    delete[] arr;
}