日期:2014-05-16  浏览次数:20872 次

创建消息队列,接受消息失败,接受程序再发送错误消息给发送程序//程序能运行,不出结果
C/C++ code

#ifndef BANK_P_H
#define BANK_P_H

struct account{
      int account_id;
      char account_name[10];
      double account_salary;
};

struct Bank{
     long mtype;
     struct account account_m;
};

struct Message{
    long mtype;
    char message[20];
};

int key = 0x87111;

#endif


C/C++ code

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <signal.h>
#include "bank_p.h"

int msgid;

void init()//create message queue
{
        printf("banks' server begins to opened\n");
        msgid = msgget(key,IPC_CREAT|IPC_EXCL|0666);
        if(msgid == -1) msgid = msgget(key,0);
        if(msgid == -1) perror("banks'server begins to failed"),exit(-1);
        printf("banks'service successfully\n");
}

void service()//receive function
{
        printf("banks' server begins to operation\n");
        printf("stop:ctrl+c\n");
        struct Bank bank_server;
        struct Message message_obj;
        message_obj.mtype = 3;
        strcpy(message_obj.message,"sorry,can't receive your message comes form linet");
        while(1)
        {        //can't receive message ,and send error message to linet.
                if(msgrcv(msgid,&bank_server,sizeof(struct Bank),1,0)<=0)
                {
                        if(msgsnd(msgid,&message_obj,sizeof(struct Message),0)== -1)
                                perror("create failed"),exit(-1);
                        printf("send successfully error mesage to client\n");
                }
        }
}
void show(int signo)//free message queue function
{
        printf("\nbanks'server begins to free\n");
        msgctl(msgid,IPC_RMID,0);
        printf("banks'server has ended\n");
        exit(0);
}

int main()
{
        init();
        signal(SIGINT,show);
        service();
}



C/C++ code

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include "bank_p.h"

int main()
{
        int msgid = msgget(key,0);
        
        //send message
        struct Bank account_client_two;
        account_client_two.mtype = 2;
        account_client_two.account_m.account_id = 002;
        strcpy(account_client_two.account_m.account_name,"Edward");
        account_client_two.account_m.account_salary = 1000;
        if(msgsnd(msgid,&account_client_two,sizeof(struct Bank),0)== -1)
                perror("send message failed"),exit(1);
        printf("send message successfully\n");
        //receive error message
        struct Message message_soer;
        while(1)
        {
                if(msgrcv(msgid,&message_soer,sizeof(struct Message),3,0)<=0)
                        perror("No error"),exit(-1);
                printf("error message:%s\n",message_soer.message);
        }
}




------解决方案--------------------
如果不想阻塞,
msgrcv(msgid,&bank_server,sizeof(struct Bank),1,IPC_NOWAIT)