创建消息队列，接受消息失败，接受程序再发送异常消息给发送程序//程序能运行，不出结果

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_Hstruct 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);        }}

[解决办法]
如果不想阻塞，
msgrcv(msgid,&bank_server,sizeof(struct Bank),1,IPC_NOWAIT)

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