write.c

进程间通信的实验代码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <sys/msg.h>
#include <sys/ipc.h>
#include "message.h"
#define SEGSIZE 	sizeof(struct mymsgbuf)

//本程序并没有按要求，仅演示了数据的读写方法。
//按要求，1K的数据应该是对文件进行处理。
//即需要打开文件、读取文件内容到缓冲区、写入共享存储区
main()
{
	struct mymsgbuf studentinfo;
	int shmid;
	key_t key;
	char *segptr;
	key=ftok(".",'S');
	if((shmid = shmget(key, SEGSIZE, IPC_CREAT|IPC_EXCL|0666)) == -1)
	{
		printf("Shared memory segment exists - opening as client\n");
		/* Segment probably already exists - try as a client */
		if((shmid = shmget(key, SEGSIZE, 0)) == -1)
		{
			perror("shmget");
			exit(1);
		}
	}
	else
	{
		printf("Creating new shared memory segment\n");
	}
	/* Attach (map) the shared memory segment into the current process */
	if((segptr = shmat(shmid, 0, 0)) == -1)
	{
		perror("shmat");
		exit(1);
	}

	for (;;)
        {
	   	printf("please enter your id:");
		scanf("%s",studentinfo.id);
	   	printf("please enter your name:");
		scanf("%s",studentinfo.name);
	   	printf("please enter your age:");
		scanf("%s",&studentinfo.age);
	   	printf("please enter your E_mail:");
		scanf("%s",studentinfo.e_mail);

	   
        printf("your Info:\n");
	   	printf("\tid:\t %s\n",studentinfo.id);
	   	printf("\tname:\t %s\n",studentinfo.name);
	   	printf("\tage:\t %d\n",studentinfo.age);
	   	printf("\tE_mail:\t %s\n\n",studentinfo.e_mail);
		//write data to share memory.
		memcpy(segptr,&studentinfo,sizeof(struct mymsgbuf));
        }
    shmctl(shmid,IPC_RMID,NULL);
	exit(0);
}