进程间通讯之消息队列（实例）

1、msgget

#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>

void get_msginfo(int msgid);

int main(void)
{
int msgid,ret;
//key=ftok();

//msgid=msgget(IPC_PRIVATE,0600);
msgid=msgget(0x555,IPC_CREAT|0600);//create or get
if(msgid==-1)
{
perror("msgget");
return 1;
}
printf("msgid:%d\n",msgid);

get_msginfo(msgid);

//del
msgctl(msgid,IPC_RMID,NULL);
return 0;
}
void get_msginfo(int msgid)
{
struct msqid_ds buf;
msgctl(msgid,IPC_STAT,&buf);

printf("max:%d bytes:%d num:%d\n",buf.msg_qbytes,buf.__msg_cbytes,buf.msg_qnum);
}

2、发送端和接收端

2.1、发送端：

#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>

#define     SIZE      32

typedef struct{
int    id;
char   name[SIZE];
float  math;
}Student_t;

struct msg{
long      type;
Student_t stu;
};

void init_msg(struct msg *s);
void show_msginfo(int msgid);

int main(void)
{
int ret,msgid;

msgid=msgget(0x555,IPC_CREAT|0646);
if(msgid==-1)    return 1;
printf("get or create msg queue success\n");

show_msginfo(msgid);
//------------------send msg--------------------
struct msg mymsg;
init_msg(&mymsg);

ret=msgsnd(msgid,&mymsg,sizeof(Student_t),0);
if(ret==-1)
{
perror("msgsnd");
return 2;
}
//-----------------------------------------------
show_msginfo(msgid);
return 0;
}
void show_msginfo(int msgid)
{
struct msqid_ds buf;
msgctl(msgid,IPC_STAT,&buf);

printf("max:%d bytes:%d num:%d\n",buf.msg_qbytes,buf.__msg_cbytes,buf.msg_qnum);
}
void init_msg(struct msg *s)
{
printf("type :");
scanf("%ld",&s->type);

printf("id   :");
scanf("%d",&s->stu.id);
printf("name :");
scanf("%s",s->stu.name);
printf("math :");
scanf("%f",&s->stu.math);
}

2.2、接收端

#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>

#define     SIZE      32

typedef struct{
int    id;
char   name[SIZE];
float  math;
}Student_t;

struct msg{
long      type;
Student_t stu;
};

void show_msginfo(int msgid);

int main(void)
{
int ret,msgid;

msgid=msgget(0x555,0444);（客户端都是只读就可以了）
if(msgid==-1){
perror("msgget");
return 1;
}
printf("get or create msg queue success\n");

show_msginfo(msgid);
//------------------send msg--------------------
struct msg mymsg;

ret=msgrcv(msgid,&mymsg,sizeof(Student_t),-4,IPC_NOWAIT);
printf("==rcv ret:%d\n",ret);
if(ret==-1)
{
perror("msgsnd");
return 2;
}
printf("type:%ld id:%d name:%s\n",mymsg.type,mymsg.stu.id,mymsg.stu.name);
//-----------------------------------------------
show_msginfo(msgid);
return 0;
}
void show_msginfo(int msgid)
{
struct msqid_ds buf;
msgctl(msgid,IPC_STAT,&buf);

printf("max:%d bytes:%d num:%d\n",buf.msg_qbytes,buf.__msg_cbytes,buf.msg_qnum);
}

#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>

#define     SIZE      32

typedef struct{
int    id;
char   name[SIZE];
float  math;
}Student_t;

void show_msginfo(int msgid);

int main(void)
{
int ret,msgid;

msgid=msgget(0x555,0644);
if(msgid==-1){
perror("msgget");
return 1;
}
printf("get or create msg queue success\n");

show_msginfo(msgid);
//------------------recv msg--------------------
char buf[64];
//ret=msgrcv(msgid,buf,20,0,MSG_NOERROR | IPC_NOWAIT);
ret=msgrcv(msgid,buf,64,0,IPC_NOWAIT);
printf("==rcv ret:%d\n",ret);
if(ret==-1)
{
perror("msgsnd");
return 2;
}
Student_t *s=(Student_t *)(buf+sizeof(long));
printf("type:%ld id:%d name:%s math:%f\n",*(long *)buf,s->id,s->name,s->math);
//-----------------------------------------------
show_msginfo(msgid);
return 0;
}
void show_msginfo(int msgid)
{
struct msqid_ds buf;
msgctl(msgid,IPC_STAT,&buf);

printf("max:%d bytes:%d num:%d\n",buf.msg_qbytes,buf.__msg_cbytes,buf.msg_qnum);
}