Thread: Randomizing Multidimensional Arrays

Originally Posted by memcpy

• Your indentation and formatting are terrible.
• Don't use system("pause") because it's not portable.
• If you want an array of O's with 15 randomly placed X's, you shouldn't hard-code the X's. Instead, you should do something like this:
  Code:

  char board[ROWS][COLUMNS] = { 'O' };

  and then place the X's.

First, what do you mean "Your indentation and formatting are terrible"? That's only what the code looks like after copy/pasting it onto this site. It looks alot better in the actual file.

http://i897.photobucket.com/albums/a...Untitled-4.jpg

Second, I use system("pause") because the executable ends the moment it initializes unless I have some sort of door stopper. Do you recommend I use cin ques, instead?

Third, I'll create an array of O's, then and have 15 X's replace random O's. How do I go about writing the code for that, though? That's the reason I created this thread.

I am not in the right mood right now and that I can write down on a note and hand to you. This infernal, god forsaken internet connection has gone down not once, but twice so far the very second I tried submitting a reply. Third times a charm but seriously, I'm ready to pull the hair out of my head and sell it on Ebay.

Now what I was going to post was that much to my own amazement, I've made progress within 15-20 minutes of your most recent reply, thanks to your most recent reply. I'd gotten the program to look through the array and replace O's with X's at random. Not all went well, however as only one of 81 total O's had been replaced; leaving 14 X's unused. This is due to the "break" no doubt but it's the only way I know to end the loop after a condition is met. Preferably there's a way to not end the loop, but bring it back to the top if the condition is met.

I've been trying for hours on end and every atempt has only caused the array to disappear entirely when the compiler is run. The code below depicts a program that displays a 9x9 array of O's and yet only a single X. If there's a way to return to the top of the loop instead of breaking it, there might be 15 X's.

PS: I've already tried using a "continue" but like many other a solution it erradicates the entire array.

Code:

#include <iostream>
#include <cstdlib>
#include <ctime>
#include <string>

　
using
namespace std;

int main()

{
　

//Initializes a 9x9 array of O's

const int ROWS = 9;
const int COLUMNS = 9;
char board[ROWS][COLUMNS] = {{'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'},

                             {'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'},

                             {'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'},

                             {'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'},

                             {'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'},

                             {'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'},

                             {'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'},

                             {'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'},

                             {'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'}};


　

//Replaces random O's with X's

int counter = 0;

    do

      {
          
        srand(static_cast<unsigned int>(time(0))); //Seed Random number
        int randomGen = rand(); // Generate random number
        int randomNum = (randomGen % 8) + 0; // Get random number between 0-8

　
      if (board[randomNum][randomNum] != 'O')

        {
            break;
        }
        

      else

        {
          board[randomNum][randomNum] = 'X';
          counter = counter + 1;
        }   
      }
    
while (counter != 15);

　


//Displays the array

for (int i=0; i < ROWS; ++i)

    {

        for (int j=0; j < COLUMNS; ++j)

        {
            cout << board[i][j];
        }
        cout << endl;
    }

　


//End of file

    cin.get();

return 0;

}

Example of output:

OOOOOOOOO
OOOOOOOOO
OOOOOOOOO
OOOOOOOOO
OOOOOOOOO
OOOOOOOOO
OOOOOOXOO
OOOOOOOOO
OOOOOOOOO

First, srand() must be called ONLY ONCE in the program. You are doing it every time through the loop and undoing the randomness each time. Please don't ask where to put it. You can figure that out yourself.

Second, you need an row and column chosen randomly. What you get with your code is loading the diagonal.

Third, remove the break. You don't want to break, you want to continue through the loop. You will exit the loop one 15 values have been placed -- that part of your code is correct.

I'll just go and say that i've had the program completed since 6:00PM but hadn't had the time to post the results until now. Thanks to memcpy's snippet of code, the program now successfully replaces 15 O's with X's instead of just one. Additional thanks to everyone else for the support. I wouldn't have been able to get this program running by now if it weren't for the assistance.

Code:

#include <iostream>
#include <cstdlib>
#include <ctime>
#include <string>

　
using namespace std;
int main()
{
　
    

//Initialize 9x9 grid

    
const int ROWS = 9;
const int COLUMNS = 9;
    
char board[ROWS][COLUMNS] = {{'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'},
                             {'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'},
                             {'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'},
                             {'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'},
                             {'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'},
                             {'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'},
                             {'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'},
                             {'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'},
                             {'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O' , 'O'}};


　
　
        
//Welcome player and explain how to play game

        cout << "Welcome to [Name Witheld]'s Minesweeper: Duke Nukem Edition" << endl;
        cout << "Instead of placing flags, you must place a single bullet" << endl;
        cout << "where you believe a mine is to blow them all up." << endl;
        cout << "If you run out of ammo, you lose.\n" << endl;
        cout << "Below is the 9x9 grid:\n\n" << endl;

　
　
    srand(static_cast<unsigned int>(time(0))); //Seed Random number
　
    


//Replace 15 O's with X's

    
for (int count = 0; count < 15; count++) //Continue loop until 15 O's were replaced with X's
    {
        
int randomNumberX = rand() % ROWS; //Assign random number to i
int randomNumberY = rand() % COLUMNS; //Assign random number to j
　
        

//Check if slot is not already an X. If not, replace existing character with X.

        
if (board[randomNumberX][randomNumberY] == 'X')
        {
            randomNumberX--;
        }
        
else
        {
            board[randomNumberX][randomNumberY] = 'X';
        }
    }
　
    


//Displays 9x9 tile grid

    
for (int i=0; i < ROWS; ++i)
    {
        
for (int j=0; j < COLUMNS; ++j)
        {
            cout << board[i][j];
        }
        cout << endl;
    }
　
　
    


//Present player a list of options

        
int modeChoice;
    
        cout << "\nEnter '1' to enter reticle placement mode." << endl;
        std::cin >> modeChoice;
　
　
    


//Gunfire program is chosen
    
//Get player input

    
if (modeChoice == 1)
    {
    
int ammo = 1;
    
int fireInputX;
    
int fireInputY;

    
        cout << "Select 'X' and 'Y' values between 0-8" <<endl;
        cout << ammo << " round(s) are in the chamber.\n" << endl;
        cout << "Enter fire input Y" << endl;
        std::cin >> fireInputY;
        cout << endl;
        cout << "Enter fire input X" << endl;
        std::cin >> fireInputX;
        cout << endl;

        
        

//If coordinates are an 'X', you win

        
if (board[fireInputY][fireInputX] == 'X')
        {
            cout << "YOU WIN" << endl;
            cin.get();
           
        }
        


//If coordinates are an 'O', you lose

        
elseif (board[fireInputY][fireInputX] == 'O')
        {
            ammo == ammo - 1;
            cout << "YOU LOSE" << endl;
            cin.get();
        }
    }
    
　
    cin.get();
return
 0;
}

Example of Output:

Welcome to [Name Witheld]'s Minesweeper: Duke Nukem Edition
Instead of placing flags, you must place a single bullet
where you believe a mine is to blow them all up
If you run out of ammo, you lose
Below is the 9x9 grid:

XOOOOOOXO
OOOOOXOOO
OOXOOOOOO
OOOOXOOXO
OXOOOOXOO
OOOOXOOOO
OOOOOXOOO
OOXOOOOXO
OOOXOOXXO

Enter '1' to enter reticle placement mode.
1

Select 'X' and 'Y' values between 0-8
1 round(s) are in the chamber.

Enter fire input Y
5

Enter fire input X
4

YOU WIN