I am designing a console-based Sudoku. According to the game, you can change entries as you move along the board. I've used a 2d array to store the values but the problem here is that I cannot make some of the entries constant as in the sudoku game where some values on the board cannot be changed so the user must reach a solution following those entries. So my question is:

- How can I make some of the entries constant here?

I have attached the code below

#include <windows.h>
#include <iostream>
#include <conio.h>
using namespace std;

#define KEY_UP 72
#define KEY_DOWN 80
#define KEY_LEFT 75
#define KEY_RIGHT 77

class Sudoku
{
    int wholeArray[9][9];
    int number;

public:
    void setArray(void);
    void displayArray(int& x, int& y);
    void readNumber(void);
    void setPositions(int& x, int& y);
    void changeEntry(int &x, int &y);
};

void setConsoleColor(int textColor, int bgColor) {
    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), (textColor   (bgColor * 16)));
}

void Sudoku::setArray(void)
{
    for (int i = 0; i < 9; i  )
    {
        for (int j = 0; j < 9; j  )
        {
            wholeArray[i][j] = 0;
        }
    }
}

void Sudoku::displayArray(int& x, int& y)
{
    setConsoleColor(11, 0);
    cout << "\t\b\b\b1 2 3   4 5 6   7 8 9\n";
    cout << "   -------------------------\n";
    for (int i = 0; i < 9; i  )
    {
        cout << i   1 << "  | ";
        for (int j = 0; j < 9; j  )
        {
            if (x == i && y == j)
                setConsoleColor(0, 11);
            cout << wholeArray[i][j];
            setConsoleColor(11, 0);
            cout << " ";

            if ((j   1) % 3 == 0)
                cout << "| ";
        }
        cout << endl;
        if ((i   1) % 3 == 0)
            cout << "   -------------------------\n";
    }
}

void Sudoku::readNumber(void)
{
    cout << "Enter number you want to enter (from 1-9): ";
    cin >> number;
}

void Sudoku::setPositions(int& x, int& y)
{
        char key = _getch();
        if (key == KEY_UP)
            x--;
        if (key == KEY_DOWN)
            x  ;
        if (key == KEY_LEFT)
            y--;
        if (key == KEY_RIGHT)
            y  ;

        if (x < 0)
            x = 8;
        else if (x > 8)
            x = 0;

        if (y < 0)
            y = 8;
        else if (y > 8)
            y = 0;

        if (key == 'x')
            exit(0);
        if (key == 'v')
            changeEntry(x, y);
        system("cls");
}

void Sudoku:: changeEntry(int& x, int& y)
{
    int entry;
    do
    {
        cout << "Enter value:\t";
        cin >> entry;
    } while (entry < 1 || entry > 9);

    wholeArray[x][y] = entry;
}

int main()
{
    int x = 0, y = 0, entry;

    Sudoku s1;
    s1.setArray();

    s1.displayArray(x, y);
    while (1)
    {
        s1.setPositions(x, y);
        s1.displayArray(x, y);
    }
    return 0;
}

CodePudding user response：

Can I make some values of an array unchangeable in c ?

You can make an entire array unchangeable by making it an array of const objects. You can make an array entirely changeable by making it an array of non-const objects. C arrays are homogeneous, so you cannot have mix of differently qualified types.

What you could have is an array of std::variant<T, const T>. Or, you could simply write a class that wraps the array that allows modification only through member functions. Those member functions can refuse to change elements that you deem to be unchangeable.

CodePudding user response：

You can create another array forbidden[9][9] and the position that you don't want the user to change mark them for example

forbidden[1][0] = 1;
forbidden[2][5] = 1;
forbidden[3][7] = 1;

and when you want to change the value of your original array check the forbidden array first

if (key == 'v' && forbidden[x][y] != 1)
    changeEntry(x, y);