C++ 中的 Fork() 和 Wait()

Question

我在 C++ 中有一个类，它调用 fork() 然后 wait()s 让子进程完成，但是当我尝试这样做时出现编译器错误。

代码如下：

#include <iostream>
#include <string>
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

using namespace std;

/* Connection class */
class Connection {
    string destination, userName, computerName;

public:
    /*  constructor for class
    You must pass it two strings. The first must be either the word "server" or the word "client".
    This will tell us which machine we want to connect to. The second will specify the username
    with which to connect to that machine.
    */
    Connection(string state, string user="default_username")
    {
        if(state == "server")
        {
            cout << "You've chosen to connect to the 'server'.\n";
            destination = "user.palmetto.clemson.edu:";
            userName = user;
            cout << "Destination: " << destination << ", Username: " << userName << "\n";
            cout << "Full connect argument: " << userName << "@" << destination << "\n";
        } else if (state == "client")
        {
            cout << "You've chosen to connect to the 'client'.\n";
            destination = "NIElaparo.ces.clemson.edu:";
            userName = user;
            cout << "Destination: " << destination << ", Username: " << userName << "\n";
            cout << "Full connect argument: " << userName << "@" << destination << "\n";
        } else
            cout << "Error. Please enter either 'server' or 'client' for first argument in Connection().\n";

      string atString = "@";
      computerName = userName + atString + destination;
    }
    /*  Send function for class
    Accepts a string as an argument which contains the name of the file to be sent. And then it uses
    exec() system calls to use "scp" to send the file.
    Note: this assumes that passwordless ssh has been set up between the client and server machines.
    */




    /* ITS IN THIS FUNCTION THAT I GET THE ERROR. I SPLIT THE PROCESS WITH FORK, RUN 
       EXECL() AND THEN WAIT() ON THE CHILD PROCESS */
    int Send(string fileName)
    {
      pid_t pid;
       // char * parmList[] = {"scp", fileName, destination, NULL};
      int    status;

      if ((pid = fork()) < 0) {     /* fork a child process           */
         printf("*** ERROR: forking child process failed\n");
         exit(1);
      }
      else if (pid == 0) {          /* for the child process:         */
         if (execl("scp", fileName.c_str(), computerName.c_str(), NULL) < 0) {     /* execute the command  */
            printf("*** ERROR: exec failed\n");
            exit(1);
         }
      }
      else {                                  /* for the parent:      */
         while (wait(&status) != pid)       /* wait for completion  */
            ;
      }
    }
};


int main()
{
    Connection *con = new Connection("server");
    /* I'm just doing this to see if this works to create the string "testgoingnow". Who knows. */
    //string string = "test".append("going").append("now\n");
   string string1 = "test";
   string at = "@";
   string string2 = "going";
   string new_string = string1 + at + string2;
   cout << new_string << "\n";

   Send("test.txt");

    //cout << string;

    return 0;
}

我得到这个编译器错误：

connection.cpp: In member function ‘int Connection::Send(std::string)’:
connection.cpp:64: error: no matching function for call to ‘wait::wait(int*)’
/usr/include/bits/waitstatus.h:68: note: candidates are: wait::wait()
/usr/include/bits/waitstatus.h:68: note:                 wait::wait(const wait&)

Answer 1

也许你需要包含正确的标题，试试

#include <sys/wait.h>