Merge branch 'master' of ssh://master.iot-yun.club:2280/raspberrypi

guowenxue

2019-08-03 e6e79ca02d323e9a10f115ade7ba6ac9c0d7a3f0

 apue/1.File_IO/ds18b20.c

@@ -116,5 +116,7 @@
    /* convert string value to float value */
    *temp = atof(ptr)/1000;
   
    close(fd);

    return 0;
}