Thread: cannot do threading but maybe forking ???

hi,

how would one pass a vector to a forked process and afterwords collect the data from that array:


example:

Code:

using namespace std;
int main (){

  pid_t pid;
  int status;
  vector<pid_t> pidarray(2);
  vector<int> vec(10,0);
  vector<vector<int>> a(2,vec);
  for (int i = 0; i< 2; i++){
    pid = fork();

    if (pid == pid_t(0)) {
        for(int z = 0; z <  10;z++){a[i][z] = z;}
        exit(0);
    }
    else if (pid > pid_t(0)){
        pidarray[i] = pid;
    }else{
        cerr << "failed\n";
        exit(1);
    }
  }

  for(int i =0; i<2;i++)
     waitpid(pidarray[i], &status, 0);

  cout << endl;
  for(int i =0; i< 2; i++){
     cout << endl;
     for(int z = 0; z <10;z++){
        cout << a[i][z]<< endl;
     }
  }


  return 0;

}

so i would like for my results obtained in forked processes to be in my a vector. Is this possible to do ??

thnx

Why do you need to fork instead of using a thread? Using fork will lock you to POSIX/Linux. Threads are platform independent.
fork is also problematic. While it copies all the current memory over to the new process, the two processes do not share the same memory space, so you cannot easily copy back the results. That means you need some inter-process communication.

Once you're in the domain of creating processes, then the simple and obvious way of sharing information is to use the file system.

An alternative is to setup a pipe() between the parent and child processes.