Tukukkk

it's my firt post here.

I have done this:

#include <iostream>

#include <ctime>

using namespace std;



const int width = 60;

const int height = 20;



void generujpole(char pole[height])

{

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

{

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

    {

    int maluj = rand()%2;

    if(maluj == 0) pole[i][j] = ' ';

    else pole[i][j] = 'o';

    }

}

}



void wypiszpole(char pole[height])

{

cout << "+------------------------------------------------------------+"<<endl;

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

    {

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

    {

    cout << pole[i][j];

    }

cout << endl;

}

cout << "+------------------------------------------------------------+"<<endl;

}



int main()

{

srand(time(NULL));

char plansza[60][20];



generujpole(plansza);

wypiszpole(plansza);



return 0;

}

The language is polish, so don't be confused with the terminology.

I'm trying to make Conway's "Game of life", it's only the beginning for now, and
I do not really know what to do next. Right now, my problem is how to set a probability of drawing "o" to 15% vs 85% for blank space ""?

If it's possible, I just want to make a little change in my code, not doing something really ambitious and unknown, because probably I wouldn't understand it.

I hope there is someone who's willing to help me with this. :)

You have basically got it already, except at the moment you are limiting yourself to 50% probability with the %2 part.

Try increasing that to % 100, and instead of comparing the result with == 0, compare with < 15, which will occur approximately 15% of the time.

You should use the random header (rand is not advised):

#include <random>

And then in your function:

std::mt19937 rng;

rng.seed(std::random_device()());

std::uniform_int_distribution<std::mt19937::result_type> dist(0,99); // distribution in range [0, 100[



std::cout << dist(rng) << std::endl;

Then check if dist(rng) is lower than 15 to have your percentage.

Of course, the dist and the rng should be outside your generujpole function and be passed in.

Right now, my problem is how to set a probability of drawing "o" to
15% vs 85% for blank space ""?

Another possibility. I like the following because this approach can easily show the distribution, and is easily modified.

#include <iostream>

using std::cout, std::endl;



#include <iomanip>

using std::setw;



#include <string>

using std::string;



#include <vector>

using std::vector;



#include <algorithm>

using std::shuffle;



#include <random>   // random_device

using std::random_device, std::mt19937_64;







class T990_t

{

   vector<char>::size_type     sz100;

   vector<char>::size_type percent15;  // 15 percent

   vector<char>::size_type percent85;  // 85 percent

   vector<char> gameBoard;



public:

   T990_t() : sz100 (20*60) , percent15 (0) , percent85 (0), gameBoard()

      {

         gameBoard.reserve(sz100);

      }



   ~T990_t() = default;



   int operator()() { return exec(); }



private: // methods



   int exec()

      {

         // initialize the gameBoard to DEAD state

         for (vector<char>::size_type  i=0; i < sz100; ++i)

            gameBoard.push_back('~'); // DEAD state (using visible char)



         // how might we set 15% of gameboard to ALIVE?

         setGameBoardAlive ( 15U );



         showGameBoard (" at 15% (note poor (but valid) sequence) ");



         // how 'distribute' the 15% ?

         shuffleGameBoard();



         showGameBoard(" after shuffle ");



         return 0;

      }



   void setGameBoardAlive(vector<char>::size_type percentAlive)

      {

         percent15 = ( sz100 * percentAlive ) / 100;  // 15 percent

         percent85 = ( sz100 - percent15    );        // 85 percent



         cout << "n  100 percent: " << setw(5) << sz100

              << "n   15 percent: " << setw(5) << percent15

              << "n   85 percent: " << setw(5) << percent85

              << "n         sum : " << setw(5) << (percent15 + percent85)

              << endl;



         for (vector<char>::size_type i = 0; i < percent15; i++) {

            gameBoard[i] = 'o'; // ALIVE state

         }

      }



   void showGameBoard(string lbl)

      {

         int ll = 0;

         cout << "n  GameBoard " << lbl << ": n  ";

         for (vector<char>::size_type i=0; i<sz100; i++)

         {

            cout << gameBoard[i];

            ll += 1;

            if (ll > 100) { cout << "n  "; ll = 0; }

         }

         cout << endl;

      }



   void shuffleGameBoard()

      {

         cout << "n  gameBoard std::shuffle n  ";

         random_device rd;

         mt19937_64 gen(rd());

         shuffle (gameBoard.begin(), gameBoard.end(), gen);

         //cout << "n  ";

      }





}; // class T990_t





int main(int , char**) { return T990_t()(); }

With possible output:

  100 percent:  1200

   15 percent:   180

   85 percent:  1020

         sum :  1200



  GameBoard  at 15% (note poor (but valid) sequence) : 

  ooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo

  ooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo~~~~~~~~~~~~~~~~~~~~~~

  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



  gameBoard std::shuffle 



  GameBoard  after shuffle : 

  ~~o~~~~~o~~~~~~~o~~~~~~~~~o~~~~~~o~o~o~~~~~~~~~~~~~~~o~~~~~~~o~~~~~~o~~~~~~~~~o~o~~~~~o~~~~o~~o~~~~~~

  ~oo~~o~~oo~o~~~~~oo~~~~~~o~~~~~~~~~~~~~o~~~~~~~~~~~~~~~~o~~~~o~~~~o~~~~o~o~oo~~~o~~~~~o~~~~~~~~~~o~~o

  ~~~~o~~~~~o~~~~~~~~~~~~~o~~~oo~~~~~~~~~~~~~o~~o~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~o~~o~~o~~~~~~~

  ~~~~~~o~~~oo~~~~o~~~o~~~~~o~~~~~o~~o~~~~~~~~~~o~~~~~~~~~~o~~~~~~~~~~~o~~o~o~~~~~~~~~o~~~~~~o~~~~~~~~~

  ~o~~~~~~~~~~~~oo~~~~~~~~~~~o~~~~~~o~o~~o~~~~~~~~~oo~~~~~oo~~~~o~~~~~~~~o~~o~~~~~~~o~~~~~~~o~~~~~~~~o~

  ~~~~~~~~~~~~~~o~~~~o~~~~~o~~~~~oo~~~~~~o~~~~~~~~o~~~~~~oooo~~~~~~~o~~o~~~~~~~~~~~~~~~~~~~~o~~~~~o~~~~

  ~~~~~~~~~~~~~~o~oo~~~~~~~~~~~~o~~~~~~~~~o~oo~~~~~~~~~~~~~~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~~~~~~~~~~~~~~~~~~~~~~~~~~~~oooo~~~o~~~~~~oo~~~~o~o~o~~~~~~o~~~~~~~~o~o~o~~~~~~~o~~~~~oo~~~~~~~~~~~~

  o~~~~~~~~~~~~~~~~~~o~~oo~~~~~o~~~~o~~o~~~oo~~~~~oo~~~~o~o~~~o~~~o~~~o~~~~~o~~~~o~~~~~o~~~o~~~~~oo~~~~

  ~~~o~~~~oo~~~~~~~~~~oo~~~~~~o~~~o~~~~~~~~~~~~~~~~~~~~~~o~~~~~~~~~~~~~~~~~o~~~~~~~~~~~~~~o