Thread: Looping and inputing

  1. #1
    Registered User
    Join Date
    Jul 2002
    Posts
    4

    Unhappy Looping and inputing

    I have just started to learn C++, and am trying to make a O's & X's program to test what I have learned from the tutorials here.

    My problem is that after the first input line, every other input line is outputed twice, here's the problem code:

    Code:
    void game()
    {
      char place[2], piece='O';
      int x=0, y=0;
      draw_board();
    
      while(!win())
      {
        cout << endl << piece << " enter a position>";  // this is the line outputed twice
        cin.getline(place,3,'\n');
        switch(place[0])
        {case 't': x=0; break;
         case 'm': x=1; break;
         case 'b': x=2; break;
         default : x=3; 
        }
        switch(place[1])
        {case 'l': y=0; break;
         case 'm': y=1; break;
         case 'r': y=2; break;
         default : y=3;
        }
        if(x!=3 && y!=3)
        {
          board[x][y]=piece;
          chg_plr(&piece);
          draw_board();
        }
      };
    }
    can anyone offer an idea why the line is printed twice?

    if you wish to see the rest, it is included as an attachment (I know that win isn't properly coded yet, I just used that temporarily)

  2. #2
    Registered User raimo's Avatar
    Join Date
    Jun 2002
    Posts
    107
    The program crashed with me because you have there char place[2] but the user usually enters two characters and '\0' is added to the end. char place[3] fixes that problem.

  3. #3
    Registered User
    Join Date
    Jul 2002
    Posts
    4
    Thanks for that, I wonder why Visual C++ didn't spot that

  4. #4
    Registered User raimo's Avatar
    Join Date
    Jun 2002
    Posts
    107
    Actually it's because cin.getline(place,3,'\n'); can't know how big the passed buffer is. In C++ you can also use std::strings:

    // #include <string>
    std::string place;
    std::getline(std::cin,place);

  5. #5
    Registered User
    Join Date
    Jul 2002
    Posts
    4
    what's a std::string, I've never seen that before

Popular pages Recent additions subscribe to a feed