IO编程--两进程间的实时通信

一、使用有名管道实现两个进程之间的相互通信

代码如下：

创建有名管道文件

#include <myhead.h>
int main(int argc, const char *argv[])
{
	if(mkfifo("myfifo",0664)==-1)
	{
		perror("create error");
		return -1;
	}
	if(mkfifo("myfifo_1",0664)==-1)
	{
		perror("create error");
		return -1;
	}
	getchar();
	unlink("myfifo");
	unlink("myfifo_1");
	return 0;
}

进程A通信

#include <myhead.h>
sem_t sem;
void* task(void *arg)
{
	sem_wait(&sem);
//	printf("subthread A\n");
	int rfd=open("myfifo_1",O_RDONLY);
	if(rfd==-1)
	{
		perror("open error");
		return NULL;
	}
	char rbuf[128]="";
	while(1)
	{
		bzero(rbuf,sizeof(rbuf));
		read(rfd,rbuf,sizeof(rbuf));
		printf("\n接收到信息：%s\n",rbuf);
		if(strcmp(rbuf,"bye")==0)
			break;
	}
	pthread_exit(NULL);
}
int main(int argc, const char *argv[])
{
	sem_init(&sem,0,0);
	pthread_t tid=-1;
	if(pthread_create(&tid,NULL,task,NULL)!=0)
	{
		printf("create error\n");
		return -1;
	}
	printf("main thread A\n");
	int wfd = open("myfifo",O_WRONLY);
	if(wfd==-1){
		perror("open error");
		return -1;
	}
	//向管道中写入文件
	char wbuf[128]="";
	while(1){
		bzero(wbuf,sizeof(wbuf));
		printf("请输入：");
		fgets(wbuf,sizeof(wbuf),stdin);
		wbuf[strlen(wbuf)-1]=0;
		//写入管道
		write(wfd,wbuf,sizeof(wbuf));
		printf("发送成功\n");
		sem_post(&sem);
		if(strcmp(wbuf,"bye")==0)
			break;
	}
	close(wfd);
	pthread_join(tid,NULL);
	sem_destroy(&sem);
	return 0;
}

进程B通信功能

#include <myhead.h>
sem_t sem;
void* task(void *arg)
{
	sem_wait(&sem);
//	printf("subthread\n");
	int wfd=open("myfifo_1",O_WRONLY);
	if(wfd==-1){
		perror("open error");
		return NULL;
	}
	char wbuf[128]="";
	while(1){
		bzero(wbuf,sizeof(wbuf));
		printf("请回答：");
		fgets(wbuf,sizeof(wbuf),stdin);
		wbuf[strlen(wbuf)-1]=0;
		write(wfd,wbuf,sizeof(wbuf));
		printf("发送成功\n");
		if(strcmp(wbuf,"bye")==0)
			break;
	}
	pthread_exit(NULL);
}
int main(int argc, const char *argv[])
{
	pthread_t tid=-1;
	sem_init(&sem,0,0);
	if(pthread_create(&tid,NULL,task,NULL)!=0)
	{
		printf("create error");
		return -1;
	}
	printf("main thread\n");
	int rfd=open("myfifo",O_RDONLY);
	if(rfd==-1)
	{
		perror("open error");
		return -1;
	}
	char rbuf[128]="";
	while(1){
		bzero(rbuf,sizeof(rbuf));
		read(rfd,rbuf,sizeof(rbuf));
		printf("\n接收到的信息：%s\n",rbuf);
		sem_post(&sem);
		if(strcmp(rbuf,"bye")==0)
			break;
	}
	close(rfd);
	pthread_join(tid,NULL);
	sem_destroy(&sem);
	return 0;
}

二、思维导图