/*********************************************************************************
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* Copyright: (C) 2025 LingYun IoT System Studio
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* All rights reserved.
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*
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* Filename: iotc.c
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* Description: This is temperature monitor client program runs on RPi
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*
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* Version: 1.0.0(10/20/2025)
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* Author: Guo Wenxue <guowenxue@gmail.com>
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* ChangeLog: 1, Release initial version on "10/20/2025 09:48:51 PM"
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*
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* Pin connection:
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*
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* vcc --- #Pin1 ( 3.3v )
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* DQ --- #Pin7 (BCM GPIO4)
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* GND --- #Pin9 ( GND )
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*
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* /boot/config.txt:
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*
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* dtoverlay=w1-gpio-pullup,gpiopin=4
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*
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********************************************************************************/
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#include <stdio.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <string.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <dirent.h>
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#include <time.h>
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#include <math.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <getopt.h>
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void print_usage(char *progname)
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{
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printf("%s usage: \n", progname);
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printf(" -i(--ipaddr): sepcify server IP address\n");
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printf(" -p(--port): sepcify server port.\n");
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printf(" -h(--Help): print this help information.\n");
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return ;
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}
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int ds18b20_get_temperature(float *temp);
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int main(int argc, char **argv)
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{
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int conn_fd = -1;
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int rv = -1;
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char buf[1024];
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char *servip = "127.0.0.1";
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int port = 0;
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struct sockaddr_in serv_addr;
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float temp;
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int interval = 10;
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int ch;
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struct option opts[] = {
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{"interval", required_argument, NULL, 'I'},
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{"ipaddr", required_argument, NULL, 'i'},
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{"port", required_argument, NULL, 'p'},
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{"help", no_argument, NULL, 'h'},
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{NULL, 0, NULL, 0}
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};
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/* parser command line input arguments */
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while( (ch=getopt_long(argc, argv, "I:i:p:h", opts, NULL)) != -1 )
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{
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switch(ch)
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{
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case 'I':
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interval=atoi(optarg);
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break;
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case 'i':
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servip=optarg;
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break;
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case 'p':
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port=atoi(optarg);
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break;
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case 'h':
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print_usage(argv[0]);
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return 0;
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}
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}
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/* socket client must specify server IP address and port */
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if( !servip || !port )
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{
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print_usage(argv[0]);
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return 1;
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}
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/* create TCP socket */
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conn_fd = socket(AF_INET, SOCK_STREAM, 0);
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if(conn_fd < 0)
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{
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printf("create socket failure: %s\n", strerror(errno));
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return 2;
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}
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/* set server IP address and port into $server_addr */
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memset(&serv_addr, 0, sizeof(serv_addr));
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serv_addr.sin_family = AF_INET;
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serv_addr.sin_port = htons(port);
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inet_aton( servip, &serv_addr.sin_addr );
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/* connect to socket server */
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if( connect(conn_fd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
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{
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printf("connect to server [%s:%d] failure: %s\n", servip, port, strerror(errno));
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return 3;
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}
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while(1)
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{
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/* DS18B20 sample temperature */
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if( ds18b20_get_temperature(&temp) < 0 )
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{
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printf("ERROR: ds18b20 get temperature failure\n");
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return 1;
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}
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snprintf(buf, sizeof(buf), "Current temperature: %.3f ℃", temp);
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/* send message to socket server */
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if( write(conn_fd, buf, strlen(buf)) < 0 )
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{
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printf("Write data to server [%s:%d] failure: %s\n", servip, port, strerror(errno));
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goto cleanup;
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}
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printf("Send temperature: %.3f ℃ to socket server okay\n", temp);
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sleep(interval);
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}
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cleanup:
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close(conn_fd);
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return 0;
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}
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/* File Content:
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pi@raspberrypi:~/guowenxue $ cat /sys/bus/w1/devices/28-041731f7c0ff/w1_slave
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3a 01 4b 46 7f ff 0c 10 a5 : crc=a5 YES
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3a 01 4b 46 7f ff 0c 10 a5 t=19625
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*/
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int ds18b20_get_temperature(float *temp)
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{
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char w1_path[50] = "/sys/bus/w1/devices/";
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char chip[20];
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char buf[128];
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DIR *dirp;
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struct dirent *direntp;
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int fd =-1;
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char *ptr;
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float value;
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int found = 0;
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int rv = 0;
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if( !temp )
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{
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return -1;
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}
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/*+-------------------------------------------------------------------+
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*| open dierectory /sys/bus/w1/devices to get chipset Serial Number |
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*+-------------------------------------------------------------------+*/
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if((dirp = opendir(w1_path)) == NULL)
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{
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printf("opendir error: %s\n", strerror(errno));
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return -2;
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}
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while((direntp = readdir(dirp)) != NULL)
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{
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if(strstr(direntp->d_name,"28-"))
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{
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/* find and get the chipset SN filename */
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strcpy(chip, direntp->d_name);
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found = 1;
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break;
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}
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}
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closedir(dirp);
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if( !found )
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{
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printf("Can not find ds18b20 in %s\n", w1_path);
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return -3;
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}
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/*+------------------------------------------------------------------+
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*| Generate DS18B20 full path: /sys/bus/w1/devices/28-xx/w1_slave |
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*+------------------------------------------------------------------+*/
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strncat(w1_path, chip, sizeof(w1_path)-strlen(w1_path));
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strncat(w1_path, "/w1_slave", sizeof(w1_path)-strlen(w1_path));
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/*+------------------------------------------------------------------+
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*| Open and read temperature: /sys/bus/w1/devices/28-xx/w1_slave |
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*+------------------------------------------------------------------+*/
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if( (fd=open(w1_path, O_RDONLY)) < 0 )
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{
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printf("open %s error: %s\n", w1_path, strerror(errno));
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return -4;
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}
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if(read(fd, buf, sizeof(buf)) < 0)
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{
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printf("read %s error: %s\n", w1_path, strerror(errno));
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rv = -5;
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goto cleanup;
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}
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ptr = strstr(buf, "t=");
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if( !ptr )
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{
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printf("ERROR: Can not get temperature\n");
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rv = -6;
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goto cleanup;
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}
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ptr+=2;
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/*+------------------------------------------------------------------+
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*| Convert temperature string value to float value |
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*+------------------------------------------------------------------+*/
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*temp = atof(ptr)/1000;
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cleanup:
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close(fd);
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return 0;
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}
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