UNIX环境高级编程学习之第三章文件IO-文件读操作

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
int err_sys(const char * str)
{
	printf("%s/n", str);
	exit(-1);
	return 0;
}
int main(int argc, char *argv[])
{
	int fd;
	fd = open("./a.txt", O_RDONLY);
	if (-1 == fd)
	{
		err_sys(strerror(errno));
	}
	int i;
	double d;
	float  f;
	char   c;
	char str[100] = { '/0' };
	int ret = read(fd, &i, sizeof(i));
	if (ret != 4)
	{
		err_sys("read error!");
	}
	ret = read(fd, &d, sizeof(double));
	if (ret != sizeof(double))
	{
		err_sys("read error! ");
	}
	ret = read(fd, &f, sizeof(f));
	if (ret != sizeof(f))
	{
		err_sys("read error!");
	}
	ret = read(fd, &c, sizeof(c));
	if (ret != sizeof(c))
	{
		err_sys("read error!");
	}	
	ret = read(fd, str, sizeof(str));
	if (ret != sizeof(str))
	{
		err_sys("read error!");
	}
 	close(fd); 	
	printf("i=%d, d=%lf, f=%f, c=%c, str=%s/n", i, d, f, c, str);
}