fork()函数

foo.h

#include <iostream>

class foo
{
public:
   
    foo()
    {
        std::cout<<"foo constructor
";
    }
    
    ~foo()
    {
        std::cout<<"foo destructor
";
    }
    
    void doit()
    {
        std::cout<<"foo doit
";
    }
    
};

main.cpp

#include "foo.h"

extern "C"
{
    #include <unistd.h>
    #include <stdio.h>
}

int main()
{
    int count = 0;
    foo f;
    pid_t pid = fork(); //fork是把进程当前的情况拷贝一份,fork只拷贝下一步要执行的代码到新的进程
    if (pid < 0)
        std::cout<<"error in fork"<<std::endl;
    else if (pid == 0)
    {
        std::cout<<"i am child process"<<std::endl;
        ++count;
        std::cout<<"child process id : "<<getpid()<<std::endl;
    }
    else
    {
        std::cout<<"i am parent process"<<std::endl;
        ++count;
        std::cout<<"parent process id : "<<getpid()<<std::endl;
    }
    
    f.doit();
    std::cout<<"count : "<<count<<std::endl;
    
    return 0;
}

　　

输出：