Multiple Processes and Threads

This is a discussion on Multiple Processes and Threads within the C Programming forums, part of the General Programming Boards category; I am making a connect four game and I would like to have Multiple processes and pipes, but I'm not ...

  1. #1
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    Multiple Processes and Threads

    I am making a connect four game and I would like to have Multiple processes and pipes, but I'm not sure where to start. I know you have to use fork and pipe, but when I fork just before the start of the game I get the same result for each game. I'm just confused where to go from here. Any suggestion would be greatly appreciated. Below is some of my code, I remover the parts for checking for wins, because I is not necessary to see.

    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #include <unistd.h>
    #include <time.h>
    
    
    int *moves;
    //int **Board;
    int w;
    
    
    void display(int ** Board,int rows, int columns);
    int** build_board(int N);
    int makeMove(int** Board, int player);
    int checkVictory(int** Board);
    int checkHorr(int** Board);
    void AI_move(int** Board,int player, int player2);
    void play(int **Board);
    
    
    
    
    int main(){
        
        srand((int) time(NULL));
    
    
        int width= 8;
        w=8-1;
        
        int** Board=build_board(width);
        int **Board2=build_board(width);
        
        //display(width, length);
    
    
        int i, check;
        
        if(fork()==0){
            play(Board);
        }else{
            puts("In Else");
            play(Board2);
        }
    
    
        return 0;
    }
    
    
    void play(int **Board){
        
        int i, check;
        
        for (i=0; i<((w+1)*(w+1)/2); i++) {
            
            AI_move(Board,1,2);
            
            // makeMove(Board, 1);
            // display(width, width);
            
            check=checkVictory(Board);
            
            if (check==1 || check==2) {
                puts("Winning Board");
                display(Board,w+1, w+1);
                break;
            }
            
            // AI_move(Board,2,1);
            makeMove(Board,2);
            
            check=checkVictory(Board);
            
            if (check==1 || check==2) {
                puts("Winning Board");
                display(Board, w+1, w+1);
                break;
            }
            
        }
    }
    
    
    void AI_move(int**Board,int player, int player2){
        
        int i,j;
        
        for (j=0; j<=w; j++) {
            for (i=w; i>=0; i--) {
                // printf("I: %d\n", i);
                if ( j < w && Board[j][i]==0 && Board[j+1][i]!=0) {
                    Board[j][i]=player;
                    if(checkVictory(Board)==1){
                        puts("Found Winning Move");
                        display(Board,w+1, w+1);
                        return;
                    }
                    else
                        Board[j][i]=0;
                }
            }
        }
    
    
        makeMove(Board,player);
    }
    
    
    int makeMove(int** Board,int player){
        
        int a;    
        start:a= rand()%(w+1);
        int i;
        for (i=w; i>=0; i--) {
            if ((Board[i][a])==0) {
                Board[i][a]=player;
                return 1;
            }
        }
        
        goto start;    
    }
    
    
    void display(int** Board,int rows, int columns){
        
        int i,j;
        
        for (i=0; i <= w;i++){
            for (j=0;j <=w;j++){
                if (Board[i][j]==1) {
                    printf(" R ");
                }
                else if(Board[i][j]==2)
                    printf(" B ");
                    //printf(" %d ",Board[i][j]);
                else
                    printf(" - ");
            }
            printf("\n");
        }
        
    }

  2. #2
    young grasshopper jwroblewski44's Avatar
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    Why are you planning on using processes and/or threading?

  3. #3
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    Quote Originally Posted by Justin Grover View Post
    I know you have to use fork and pipe, but when I fork just before the start of the game I get the same result for each game.

    You get the same result in both processes because you initialize the pseudo-random number generator before you fork, thus the child inherits the seed from its parent. You have to call srand() after the forking in each process to get different sequences of random numbers.
    But you also need to add a constant value to one of the return values of time(NULL) because it returns the time in seconds and your computer is probably fast enough that both processes call time() within the same second.

    Example:
    Code:
    #include <stdio.h>
    #include <unistd.h>
    #include <time.h>
    #include <stdlib.h>
    #include <sys/wait.h>
    
    int main(void)
    {
    //    srand((int) time(NULL));
    
    
        if (fork() == 0)
        {
            srand(time(NULL));
            int i;
            for (i = 0; i < 10; i++)
                printf("child #%d: %d\n", i, rand() % 100);
        }
        else
        {
            // adding a constant to time(NULL) to get different seed value
            srand(time(NULL) + 99);
            int i;
            for (i = 0; i < 10; i++)
                printf("parent #%d: %d\n", i, rand() % 100);
        }
    
        int status;
        wait(&status);
        return 0;
    }
    Bye, Andreas

  4. #4
    and the hat of int overfl Salem's Avatar
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    > I am making a connect four game and I would like to have Multiple processes and pipes, but I'm not sure where to start.
    A clear description of what each pipe and process is for would be a start.

    Just throwing things in without a clear plan is a sure-fire way of making a big broken mess of a program.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

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