消息队列

msgsnd

函数的作用：写数据到消息队列

函数的原型：int msgsnd（int msgid,const void *msggp,size_t int msgflg）

函数的参数：msggp 消息、结构

msgsize:消息的字节数

msgflg:IPC_NOWAIT(写不进去直接返回)

O:知道能写进去消息为止

omsgctl

函数的作用：控制消息队列，可以删除消息

函数的原型：int msgctl(int msgid, int cmd, struct msgid_ds buf)

函数的参数：msgid:队列ID号

cmd：命令参数IPC_STAT:读取。。。的消息队列

                         IPC_SET:设置消息队列的权限

                         IPC_RMID:删除消息队列

buf：消息队列的结构类型

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <errno.h>

#include <unistd.h>

#include <sys/types.h>

#include <sys/ipc.h>

#include <sys/msg.h>

#define MAX_TEXT 512

struct my_msg_st

{

    long int my_msg_type;

 char some_text[MAX_TEXT];

};

int main(void)

{

    int running=1;

 struct my_msg_st some_data;

 int msgid;

 int msgid1;

 long int msg_to_receive=2;

 char buffer[BUFSIZ];

 /*创建消息队列*/

 msgid=msgget((key_t)1234,0666 | IPC_CREAT);

 if(msgid==-1)

 {

     fprintf(stderr,"msgget failed with error:%d\n",errno);

  exit(EXIT_FAILURE);

    }

 msgid1=msgget((key_t)2345,0666 | IPC_CREAT);

 if(msgid==-1)

 {

     fprintf(stderr,"msgget failed with error:%d\n",errno);

  exit(EXIT_FAILURE);

    }

 /*循环向消息队列中添加消息*/

 while(running)

 {

  /*读取消息*/

     if(msgrcv(msgid1,(void *)&some_data,BUFSIZ,msg_to_receive,0)==-1)

  {

      fprintf(stderr,"msgrcv failed with error: %d\n",errno);

   exit(EXIT_FAILURE);

  }

  printf("You wrote: %s",some_data.some_text);

  

    printf("Enter some text:");

  fgets(buffer,BUFSIZ,stdin);

  some_data.my_msg_type=1;

  strcpy(some_data.some_text,buffer);

  /*添加消息*/

  if(msgsnd(msgid,(void *)&some_data,MAX_TEXT,0)==-1)

  {

      fprintf(stderr,"msgsed failed\n");

   exit(EXIT_FAILURE);

  }

  /*用户输入的为“end”时结束循环*/

  if(strncmp(buffer,"end",3)==0)

  {

      running=0;

  }

 }

 exit(EXIT_SUCCESS);

}

 

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <errno.h>

#include <unistd.h>

#include <sys/types.h>

#include <sys/ipc.h>

#include <sys/msg.h>

#define MAX_TEXT 512

struct my_msg_st

{

    long int my_msg_type;

 char some_text[BUFSIZ];

};

int main(void)

{

    int running=1;

 int msgid;

 int msgid1;

 struct my_msg_st some_data;

 long int msg_to_receive=1;

 char buffer[BUFSIZ];

 /*创建消息队列*/

 msgid=msgget((key_t)1234,0666 | IPC_CREAT);

 if(msgid==-1)

 {

     fprintf(stderr,"msgget failed with error: %d\n",errno);

  exit(EXIT_FAILURE);

 }

 msgid1=msgget((key_t)2345,0666 | IPC_CREAT);

 if(msgid1==-1)

 {

     fprintf(stderr,"msgget failed with error: %d\n",errno);

  exit(EXIT_FAILURE);

 }

/*fasong*/

 while(running)

 {

  printf("Enter some text:");

  fgets(buffer,BUFSIZ,stdin);

  some_data.my_msg_type=2;

  strcpy(some_data.some_text,buffer);

  if(msgsnd(msgid1,(void *)&some_data,MAX_TEXT,0)==-1)

  {

      fprintf(stderr,"msgsed failed\n");

   exit(EXIT_FAILURE);

  }

  /*读取消息*/

     if(msgrcv(msgid,(void *)&some_data,BUFSIZ,msg_to_receive,0)==-1)

  {

      fprintf(stderr,"msgrcv failed with error: %d\n",errno);

   exit(EXIT_FAILURE);

  }

  printf("You wrote: %s",some_data.some_text);

  /*接收到的消息为“end”时结束循环*/

  if(strncmp(some_data.some_text,"end",3)==0)

  {

      running=0;

  }

  if(strncmp(buffer,"end",3)==0)

  {

      running=0;

  }

 }

 /*从系统内核中移走消息队列*/

 if(msgctl(msgid,IPC_RMID,0)==-1)

 {

     fprintf(stderr,"msgctl(IPC_RMID) failed\n");

  exit(EXIT_FAILURE);

 }

 exit(EXIT_SUCCESS);

}

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