Segmentation fault: 11 c++ Error

Question

this is my first time asking a question on this forum so here it goes. I am creating a tic-tac-toe game for practice and am using enumerators and recursion because I have never really done enumeration and could always get some recursion practice in. Well anyway I just finished coding for the player2 to take a random move and after about 3 turns it gives a segmentation fault and I cannot figure out why... I hope you guys can figure it out and thank you!

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

const int size = 3;

enum play {none,X,O};

void NPC(play (&board)[size][size],play player2) {
  srand(time(NULL));
  int tempx = rand() % 3;
  int tempy = rand() % 3;
  if(board[tempx][tempy] == none)
    board[tempx][tempy] = player2;
  else
    NPC(board,player2);
}

void getBoardState(play (&board)[size][size],int y,int x) {
  if(board[x][y] == none) std::cout << " ";
  else if(board[x][y] == X) std::cout << "X";
  else std::cout << "O";
}

void printboard(play (&board)[size][size]){
  int length = 4 * size - 1;
  for(int i = 1; i <= length; i++) {
    for(int j = 1; j <= length; j++) {
      if(i % 4 == 0 && j % 4 == 0) std::cout << "+";
      else if(i % 4 == 0) std::cout << "-";
      else if(j % 4 == 0) std::cout << "|";
      else if(i % 2 == 0 && j % 2 == 0) getBoardState(board,(i - 2)/4,(j - 2)/4);
      else std::cout << " ";
    }
    std::cout << std::endl;
  }
}

int main() {
  play player = O, player2 = X;
  bool over = false;
  play board[size][size];
  for(int i = 0; i < size; i++) {
    for(int j = 0; j < size; j++) {
      board[i][j] = none;
    }
  }
  std::string player1 = "";
  std::cout << "What would You like to be? An X or an O?" << std::endl;
  while(((player1 != "X") + (player1 != "O")) == 2) {
    std::cin >> player1;
    if(((player1 != "X") + (player1 != "O")) == 2)
      std::cout << "Invalid entry! Please enter X or an 0!" << std::endl;
    }
  if(player1 == "X") {
    player2 = O;
    player = X;}
  int tempx,tempy;
  while(!over) {
    std::cout << "Please enter an x and then a y (1 to " << size << ")" << std::endl;
    std::cin >> tempx;
    std::cin >> tempy;
    while(tempx > size || tempy > size || board[tempx-1][tempy-1] != none) {
      std::cout << "Invalid entry! Try again!" << std::endl;
      std::cin >> tempx;
      std::cin >> tempy;
    }
    board[tempx-1][tempy-1] = player;
    NPC(board,player2);
    printboard(board);
  }
  return 0;
}

Answer 1

You're running out of stack space in your recursion because you call srand(time(NULL)) every time. The random number generator should only be seeded once, in main, and not in NPC . time(NULL) returns a number of seconds, so it changes infrequently (compared to how fast your recursive function calls will occur) which will consume all available stack space.