c++ 静态成员变量在pid更新上

保存文件名 updatepid.cpp

 编译命令 g++ -lpthread -o pid updatepid.cpp

#include <stdio.h>

#include <unistd.h>

#include <pthread.h>



class Process

{

public:

    pthread_t m_ntid;

    statict int m_nPid;

public:

    Process()

   {

        m_nPid = 0;

        pthread_create(&m_ntid,NULL,mythreadfunc,NULL);

   }

   ~Process(){};

  static void updatePid()

  {

      m_nPid = getpid();

   }

   static void* mythreadfunc(void *arg)

  {

      while(1){

          updatePid();

      }

      return NULL;

  }



int Process::m_nPid = -1; //这句很重要(-1这个值无所谓),如果没有,在链接时报Process::m_nPid是undefined reference



int main()

{

    Process *p = new Process();

    while(1)

    {

        printf("%d/n",p->m_nPid);

        sleep(1);

    }

    return 0;

}