example parent is based on.

/* #include <cstdlib> */
#include <iostream>
#include <cerrno>
#include <limits>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <stdlib.h>
#include <string.h>

using namespace std;

#define  BUFSIZ  512

/*
This program sends two types of messages of type 5 and type 1.  Two different
receiving processes receive the messages of different types (msg_receiver and
msg_receiver2).
*/


struct my_msg_st {
   long int my_msg_type;
   char some_text[BUFSIZ];
};


int main(int argc, char** argv)
{

  int running = 1;
  int msgid;
  struct my_msg_st some_data;
  struct my_msg_st return_data;
  char buffer[BUFSIZ];
  long int msg_to_receive = 11;

  /* Set up the message queue */
  msgid = msgget((key_t) 1234, 0666 | IPC_CREAT);

  if (msgid == -1) {
     cout << "msgget failed" << endl;
     exit(EXIT_FAILURE);
  }

  /* Input message; send message to the queue until an "end" is encountered. */
  while (running) {
    cout << "Enter some text (5): ";
		// get the text to be put into the queue.
    cin.getline(buffer,BUFSIZ);
// set message type
    some_data.my_msg_type = 5;
	// copy message into shared memory
    strcpy(some_data.some_text, buffer);
// if the message send is set to error, end.
    if (msgsnd(msgid, (void *)&some_data, BUFSIZ, 0) == -1) {
       cout << "msgsnd failed" << endl;
       exit(EXIT_FAILURE);
    }
// else print "sent message"
    cout << "You sent a message." << endl;
// get text for second output.
    cout << "Enter some text (1): ";
    cin.getline(buffer,BUFSIZ);
// set message type
    some_data.my_msg_type = 1;
	// copy data
    strcpy(some_data.some_text, buffer);
//check for error
    if (msgsnd(msgid, (void *)&some_data, BUFSIZ, 0) == -1) {
       cout << "msgsnd failed" << endl;
       exit(EXIT_FAILURE);
    }

    cout << "You sent a message." << endl;

	// INIT TEST OF THREE RUNNING
    cout << "Enter some text (15): ";
    cin.getline(buffer,BUFSIZ);
// set message type
    some_data.my_msg_type = 15;
	// copy data
    strcpy(some_data.some_text, buffer);
//check for error
    if (msgsnd(msgid, (void *)&some_data, BUFSIZ, 0) == -1) {
       cout << "msgsnd failed" << endl;
       exit(EXIT_FAILURE);
    }

    cout << "You sent a message." << endl;
	// exit if text is "end"
    if (strncmp(buffer, "end", 3) == 0) {
       running = 0;
    }
  }

  exit(EXIT_SUCCESS);
}