What is wrong with C++ code?

Question

C++ / C#

There is a simple C++ program where I find the scalar product of matrix vectors under some conditions. Here is the code:

#include <iostream>

using namespace std;

int main() {
    // Задаю матрицу
    float a[3][3] = {{1,2,3},
                    {4,5,6},
                    {6,0,4}};
    int min = a[0][0];
    int imin = 0;
    int jmin = 0;
    
    for (int j = 0; j < 3; j++) {
        cout << a[0][j] << " | ";
    }
    cout << "\n";
    for (int j = 0; j < 3; j++) {
        cout << a[1][j] << " | ";
    }
    cout << "\n";
    for (int j = 0; j < 3; j++) {
        cout << a[2][j] << " | ";
    }
    
    // Ищу минимальный элемент и его индексы
    for (int i = 0; i < 3; i++) {
        for(int j = 0; j < 3; j++) {
            if (min > a[i][j]) {
                imin = i;
                jmin = j;
            }
        }
    }
        
    cout << "\nimin: " << imin+1 << endl;
    cout << "jmin: " << jmin+1 << endl;
    
    
    // Беру нужные векторы
    int ai[3];
    int aj[3];
    
    cout << "Строка с минимальным элементом: ";
    for (int j = 0; j < 3; j++) {
        ai[j] = a[imin][j];
    }
    for (int j = 0; j < 3; j++) {
        cout << ai[j] << " ";
    }
    
    cout << "\nСтолбец с минимальным элементом: ";
    for (int i = 0; i < 3; i++) {
        aj[i] = a[i][jmin];
    }
    for (int i = 0; i < 3; i++) {
        cout << aj[i] << " ";
    }
    
    
    //Скалярное произведение
    float scal = 0;
    
    for (int i = 0; i < 3; i++) {
        scal += ai[i] * aj[i];
    }
    cout << "\nСкалярное произведение: " << scal;
    
    return 0;
}

The program is fully working, everything is in order with it. I'm trying to rewrite it in a functional paradigm - that's where the difficulties arise:

#include <iostream>

using namespace std;

float fobr(float *af, int nf);

int main() {
    // Задаю матрицу
    int n = 3;
    float a[n][n] = {{1,2,3},
                    {4,5,6},
                    {6,0,4}};
    float sc;
    
    for (int j = 0; j < n; j++) {
        cout << a[0][j] << " | ";
    }
    cout << "\n";
    for (int j = 0; j < n; j++) {
        cout << a[1][j] << " | ";
    }
    cout << "\n";
    for (int j = 0; j < n; j++) {
        cout << a[2][j] << " | ";
    }
    
    sc = fobr(a,n);
}

//---------------------------------------------------------------------------

float fobr(float *af, int nf) {
    int min = af[0][0];
    int imin = 0;
    int jmin = 0;
    
    // Ищу минимальный элемент и его индексы
    for (int i = 0; i < nf; i++) {
        for(int j = 0; j < nf; j++) {
            if (min > af[i][j]) {
                imin = i;
                jmin = j;
            }
        }
    }
        
    cout << "\nМинимальный элемент находится в строке " << imin+1 << endl;
    cout << "Минимальный элемент находится в столбце " << jmin+1 << endl;
    
    
    // Беру нужные векторы
    int ai[nf];
    int aj[nf];
    
    cout << "Строка с минимальным элементом: ";
    for (int j = 0; j < nf; j++) {
        ai[j] = af[imin][j];
    }
    for (int j = 0; j < nf; j++) {
        cout << ai[j] << " ";
    }
    
    cout << "\nСтолбец с минимальным элементом: ";
    for (int i = 0; i < nf; i++) {
        aj[i] = af[i][jmin];
    }
    for (int i = 0; i < nf; i++) {
        cout << aj[i] << " ";
    }
    
    
    //Скалярное произведение
    float scal = 0;
    
    for (int i = 0; i < nf; i++) {
        scal += ai[i] * aj[i];
    }
    
    cout << "\nСкалярное произведение: " << scal;
    
    return scal;
}

When run, it gives errors "main.cpp:27:18: error: cannot convert 'float (*)[n]' to 'float*' for argument '1' to 'float fobr(float*, int)' sc = fobr (a,n);" and "main.cpp:33:22: error: invalid types 'float[int]' for array subscript int min = af[0][0];".
I changed float to int, it gives the same result. Apparently the problem is with the matrix. Please help find and fix the error.

PS Before that, I just rewrote another program in the functional paradigm, where there was work with three one-dimensional arrays, everything works there. I wrote it exactly EXACTLY the same way as this one, only the variables are different. I'll leave it as an example in the comments.

Answer 1

float fobr(float **af, int nf) {