在 fork() 之后，我的程序中不断获得相同的 pid

Question

This is the code

pid_t pid;
srand(time(NULL));
for (int i=0; i < 2; i++)
{
    pid = fork();
    if (pid < 0)
    {
        std::cout<< "fork failed";
        return -1;
    }

    else if (pid == 0)
    {
        std::cout<< "Process "<< i+1 << " ID: " << pid <<std::endl;
        std::thread one (threadFunction, 0);
        std::thread two (threadFunction, 1);
        std::thread three (threadFunction, 2);
        one.join();
        two.join();
        three.join();
    }
    else
    {
        wait (NULL);
        exit(0);
    }
}

The loop is supposed to create two different processes but whenever I run this the output pid is always 0. Does this mean it the same process

Answer 1

if pid == 0 your code is executing the child process. If pid is different than 0 your code execute the parent process

see section return value of the man http://man7.org/linux/man-pages/man2/fork.2.html

you can find out the real pid of the child with function getpid

http://man7.org/linux/man-pages/man2/getpid.2.html