write.c

linuxI/O的基础编程实例

/*write.c*/
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#define MAXSIZE

int main(void)
{
	int i,fd,size,len;
	char *buf="hello! I'm writing to this file!";
	char buf_r[10];
	len = strlen(buf);
/*首先调用open函数，并制定相应的权限*/
	if((fd = open("/tmp/hello.c", O_CREAT | O_TRUNC | O_RDWR, 0666))<0)
	{
		perror("open error");
		exit(1);
	}
	else
		printf("open file:hello.c %d\n",fd);
/*调用write 函数，将buf中的内容写入到文件中*/
	if((size = write(fd, buf, len))<0)
	{
		perror("write error");
		exit(1);
	}
	else
	{
		printf("write:%s\n",buf);
	}
/*调用lsseek函数将文件指针移到文件起始*/
	lseek(fd, 0, SEEK_SET);
	if((size = read(fd,buf_r,len))<0)
	{
		perror("read error");
		exit(1);
	}
	else
		printf("read from file:%s\n",buf_r);
	if(close(fd)<0)
	{
		perror("close error");
		exit(1);
	}
	else
		printf("close hello.c\n");
	exit(0);
}