C++中消息队列函数实例详解C++ 中消息队列函数实例详解1.消息队列结构体的定义typedef struct{uid_t uid; /* owner`s user id */gid_t gid; /* owner`s group id */udi_t cuid; /* creator`s user id */gid_t cgid; /* creator`s group id */mode_t mode; /* read-write permissions 0400 MSG_R 0200 MSG_W*/ulong_t seq; /* slot usage sequence number*/}ipc_perm;typedef stuct{struct ipc_perm msg_perm; /* read_write perms */struct msg *msg_first; /* ptr to first message on queue */struct msg *msg_last; /* ptr to last message on queue */msglen_t msg_cbytes; /* used bytes current on queue */msgqnum_t msg_qnum; /* current num of message on queue */msglen_t msg_qbytes; /* max # of bytes allowed on queue */pid_t msg_lspid; /* pid of last msgsnd() */pid_t msg_lrpid; /* pid of last msgrcv() */time_t msg_stime; /* time of last msgsnd() */time_t msg_rtime; /* time of last msgrcv() */time_t msg_ctime; /* time of last msgctl() */}msqid_ds;typedef struct{long mtype;char mbuf[MSGLEN];}Message;2.创建消息队列：/***************************************************Function:int msgget(ket_t key,int oflag);Explain:create or view a message queueReturn :a int indetifyInclude:sys/msg.hintroduction:oflag: 0400 msg_r0200 msg_w0600 msg_wripc_creat: NO exist and then creat a queueexist : reference a queueipc_creat|ipc_excl: NO exist and then creat a queueexist : return error****************************************************/#include<stdio.h>#include<sys/msg.h>#include<stdlib.h>int MsgGet(int key){int ret;ret=msgget(key,0600|IPC_CREAT);// ret=msgget(key,0600|IPC_CREAT|IPC_EXCL);if(ret<0)perror("creat msgid error");printf("msgid=%d/n",ret);system("ipcs -q -i ret");return ret;}int main(int argc,char *agrv[]){printf("pleasse input msgkey:");scanf("%d",&key);MsgGet(key);return 0;}3.向消息队列中发送消息msgsnd/***********************************************************************************Function:int msgsnd(int msqid,const void *ptr,size_t length,int flag)Explain:send a message to a queueReturn:len: send message len;Include:sys/msg.hIntroduction:flag: 0 : if queue full wait:1>具备存放新消息的空间2>由msqid标识的消息队列从系统中删除(返回EIDRM错误)3>调⽤线程被某个捕获的信号所中断(返回EINTR错误)IPC_NOWAIT:如果没有存放新消息的空间,函数马上返回1>指定的队列中有太多的字节2>在系统范围存在太多的消息*****************************************************************************************/#include "typemsg.h"int MsgSnd(int msqid,char *buf,int len,int flag){int ret;ret=msgsnd(msqid,buf,len,flag);if(ret<0)perror("msgsnd error");system("ipcs -q");return ret;}int main(){int msqid,len,stype;Message msgb;memset(&msgb,0,sizeof(Message));printf("msgsnd:please input msqid:");scanf("%d",&msqid);printf("please input msgtype:");scanf("%d",&stype);msgb.mtype=stype;strcpy(msgb.mbuf,"zhangweia");MsgSnd(msqid,(char *)&msgb,sizeof(Message),0);return 0;}4.从队列中获取消息 msgrcv/*********************************************************************Function:int msgrcv(int msqid,const void *ptr,size_t msglen,long type,int flag)Explain:recv message order by typemsgrcv error: Argument list too long --> msglen的长度⼩于消息体中消息的长度Para :ptr: point to message structmsglen: 由ptr指向的缓冲区中数据部分的⼤⼩,这个是该函数能够返回的最⼤数据量type: message type;1> 0:返回队列中最早的消息2> ⼤于0:返回消息队列中类型为type的第⼀个消息3> ⼩于0:返回消息队列中类型⼩于或者等于type的绝对值的消息类型中最⼩的第⼀个消息flag: 0<wait> 没有消息或者消息类型不符合的时候,线程等待响应: 1>有⼀个所请求类型的消息可以获取2>msqid的消息队列被系统删除,返回⼀个EIDRM3>调⽤线程被某个捕获的信号所中断IPC_NOWAIT:在没有数据的情况下,⽴即返回⼀个ENOMSG错误MSGNOERROR:当所接受的消息数据部分⼤于msglen长度时,获取截短的数据部分,否则返回E2BIG错误message len*********************************************************************/#include "typemsg.h"int MsgRcv(int msqid,char *buf,int msglen,long type,int flag){int ret;ret=msgrcv(msqid,buf,msglen,type,flag);if(ret<0)perror("msgrcv error");system("ipcs -q");return ret;}int main(){int msqid,len;long ttype;Message mbuf;printf("msgrcv:please input recv msqid:");scanf("%d",&msqid);MsgRcv(msqid,(char *)&mbuf,8900,0,IPC_NOWAIT);printf("recv message=%s/n",mbuf.mbuf);Put_String((unsigned char *)&mbuf,sizeof(Message));return 0;}6.消息队列的控制msgctl/**********************************************************Function:int msgctl(int msqid,int cmd,struct msqid_ds *buff)Explain:cdm: IPC_RMID; delete msqidIPC_SET:IPC_STAT: return msqid stat*********************************************************/#include "typemsg.h"int MsgCtl(int msqid,int cmd,struct msqid_ds *buff){int ret;ret=msgctl(msqid,cmd,buff);if(ret<0){perror("msgctl error");return -1;}return 0;}int main(){int msqid,type;struct msqid_ds info;printf("please input msqid /nand type(1:icp_rmid;2:ipc_stat)");scanf("%d%d",&msqid,&type);if(type==1){MsgCtl(msqid,IPC_RMID,NULL);printf("delete queue success:%d/n",msqid);}else if(type==2){MsgCtl(msqid,IPC_STAT,&info);printf("get queue stat:%d/n",msqid);}return 0;}感谢阅读，希望能帮助到⼤家，谢谢⼤家对本站的⽀持！。
