2024.02.04
写出三种进程间通信的代码示例
有名管道
创建两个有名管道文件
#include
int main(int argc, const char *argv[])
{
if(mkfifo("pipe1",0664)==-1)
{
perror("mkfifo pipe1 error");
return -1;
}
if(mkfifo("pipe2",0664)==-1)
{
perror("mkfifo pipe2 error");
return -1;
}
printf("关闭请按回车\n");
getchar();
system("rm pipe1");
system("rm pipe2");
return 0;
}
发送
#include
int main(int argc, const char *argv[])
{
int wfd=-1;
if((wfd=open("./mypipe",O_WRONLY))==-1)
{
perror("wfd open error");
return -1;
}
char wbuf[128]="";
while(1)
{
printf("请输入>>>>");
fgets(wbuf,sizeof(wbuf),stdin);
wbuf[strlen(wbuf)-1]=0;
write(wfd,wbuf,sizeof(wbuf));
if(strcmp(wbuf,"quit")==0)
{
break;
}
}
close(wfd);
return 0;
}
接收
#include
int main(int argc, const char *argv[])
{
int rfd=-1;
if((rfd=open("./mypipe",O_RDONLY))==-1)
{
perror("rfd open error");
return -1;
}
char rbuf[128]="";
while(1)
{
read(rfd,rbuf,sizeof(rbuf));
printf("收到一条消息:%s\n",rbuf);
if(strcmp(rbuf,"quit")==0)
{
break;
}
}
close(rfd);
return 0;
}
消息队列
发送
#include
struct msgbuf
{
long mtype;
char mtext[1024];
};
#define SIZE (sizeof(struct msgbuf)-sizeof(long))
int main(int argc, const char *argv[])
{
key_t key=ftok("/",'k');
if(key==-1)
{
perror("key create error");
return -1;
}
printf("key=%#x\n",key);
int msgid=msgget(key,IPC_CREAT|0664);
if(msgid==-1)
{
perror("msgget error");
return -1;
}
printf("msgid=%d\n",msgid);
struct msgbuf buf;
while(1)
{
printf("请输入您要发送的类型\n");
scanf("%ld",&buf.mtype);
printf("请输入消息内容\n");
scanf("%s",buf.mtext);
msgsnd(msgid,&buf,SIZE,0);
if(strcmp(buf.mtext,"quit")==0)
{
break;
}
}
return 0;
}
接收
#include
struct msgbuf
{
long mtype;
char mtext[1024];
};
#define SIZE (sizeof(struct msgbuf)-sizeof(long))
int main(int argc, const char *argv[])
{
key_t key=ftok("/",'k');
if(key==-1)
{
perror("key create error");
return -1;
}
printf("key=%#x\n",key);
int msgid=msgget(key,IPC_CREAT|0664);
if(msgid==-1)
{
perror("msgget error");
return -1;
}
printf("msgid=%d\n",msgid);
struct msgbuf buf;
while(1)
{
msgrcv(msgid,&buf,SIZE,10,0);
printf("收到消息%s\n",buf.mtext);
if(strcmp(buf.mtext,"quit")==0)
{
break;
}
}
return 0;
}
信号灯集
头文件
#ifndef __SEM_H__
#define __SEM_H__
#include
//信号灯集的申请,初始化信号灯,并返回信号灯集的id
int create_sem(int semcount);
//申请信号灯资源操作 p操作
int P(int semid,int semno);
//释放信号灯资源操作 v操作
int V(int semid,int semno);
//信号灯集的删除
int del_sem(int semid);
#endif
#include "sem.h"
union semun {
int val; /* Value for SETVAL */
struct semid_ds *buf; /* Buffer for IPC_STAT, IPC_SET
*/
unsigned short *array; /* Array for GETALL, SETALL */
struct seminfo *__buf; /* Buffer for IPC_INFO
(Linux-specific) */
};
int init_sem(int semid,int semno)
{
int val=-1;
printf("请输入标号为%d的灯的初始值:",semno);
scanf("%d",&val);
getchar();
union semun us;
us.val=val;
if(semctl(semid,semno,SETVAL,us)==-1)
{
perror("set val error");
return -1;
}
return 0;
}
//信号灯集的申请,初始化信号灯,并返回信号灯集的id
int create_sem(int semcount)
{
//1.创建key值
key_t key=ftok("/",'y');
if(key==-1)
{
perror("fork error");
return -1;
}
//2.通过key值创建一个信号灯集
int semid=semget(key,semcount,IPC_CREAT |IPC_EXCL|0664);
if(semid==-1)
{
if(errno==EEXIST)
{
semid=semget(key,semcount,IPC_CREAT);
return semid;
}
else
{
perror("semget error");
return -1;
}
}
//3.给信号灯集中的信号灯进行初始化操作
for(int i=0;i发送
#include "sem.h"
#define PAGE_SIZE 4096
int main(int argc, const char *argv[])
{
int semid=create_sem(2);
if(semid==-1)
{
perror("creat_sem error");
return -1;
}
//1.创建一个key值
key_t key=ftok("/",'t');
if(key==-1)
{
perror("ftok error");
return -1;
}
printf("key=%#x\n",key);
//2.通过key值创建共享内存段
int shmid=shmget(key,PAGE_SIZE,IPC_CREAT|0664);
if(shmid==-1)
{
perror("shmget error");
return -1;
}
printf("shmid=%d",shmid);
//3.将共享内存映射到用户空间
char *addr=shmat(shmid,NULL,0);
if(addr==(void *)-1)
{
printf("shmat error");
return -1;
}
//4.使用共享内存段
while(1)
{
P(semid,1);
printf("please enter");
fgets(addr,PAGE_SIZE,stdin);
addr[strlen(addr)-1]=0;
V(semid,0);
if(strcmp(addr,"quit")==0)
{
break;
}
}
//5.取消映射
if(shmdt(addr)==-1)
{
perror("shmdt error");
return -1;
}
//6.删除共享内存
if(shmctl(shmid,IPC_RMID,0)==-1)
{
perror("shmctl error");
return -1;
}
return 0;
}
接收
#include "sem.h"
#define PAGE_SIZE 4096
int main(int argc, const char *argv[])
{
int semid=create_sem(2);
if(semid==-1)
{
perror("creat_sem error");
return -1;
}
//1.创建一个key值
key_t key=ftok("/",'t');
if(key==-1)
{
perror("ftok error");
return -1;
}
printf("key=%#x\n",key);
//2.通过key值创建共享内存段
int shmid=shmget(key,PAGE_SIZE,IPC_CREAT|0664);
if(shmid==-1)
{
perror("shmget error");
return -1;
}
printf("shmid=%d",shmid);
//3.将共享内存映射到用户空间
char *addr=shmat(shmid,NULL,0);
if(addr==(void *)-1)
{
printf("shmat error");
return -1;
}
//4.使用共享内存段
while(1)
{
P(semid,0);
printf("共享内存中的数据为:%s\n",addr);
V(semid,1);
if(strcmp(addr,"quit")==0)
{
break;
}
}
//5.取消映射
if(shmdt(addr)==-1)
{
perror("shmdt error");
return -1;
}
//6.删除共享内存
if(shmctl(shmid,IPC_RMID,NULL)==-1)
{
perror("shmctl error");
return -1;
}
del_sem(semid);
return 0;
}