ESP8266 Temperature Sensor

#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include <OneWire.h>
#include <DallasTemperature.h>

// Data wire to pin D4 on the ESP8266 - GPIO 2
#define ONE_WIRE_BUS 2

// Setup oneWire
OneWire oneWire(ONE_WIRE_BUS);

// Pass our oneWire reference to Dallas Temperature. 
DallasTemperature DS18B20(&oneWire);
char temperatureCString[7];
char temperatureFString[7];

// Change the credentials below, so your ESP8266 connects to your router
const char* ssid = "YOUR WIFI SSID";
const char* password = "YOUR WIFI PASSWORD";

// Change the variable to your Raspberry Pi IP address, so it connects to your MQTT broker
const char* mqtt_server = "YOUR PI IP ADDRESS";

// Initializes the espClient.
WiFiClient esp_temp_portable;
PubSubClient client(esp_temp_portable);

// This connects your ESP8266 to your router
void setup_wifi() {
  delay(10);
  // We start by connecting to a WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("WiFi connected - ESP IP address: ");
  Serial.println(WiFi.localIP());
}

void getTemperature() {
  float tempC;
  float tempF;
  do {
    DS18B20.requestTemperatures(); 
    tempC = DS18B20.getTempCByIndex(0);
    dtostrf(tempC, 2, 0, temperatureCString);
    tempF = DS18B20.getTempFByIndex(0);
    dtostrf(tempF, 3, 2, temperatureFString);
    Serial.println(temperatureCString);
    delay(100);
  } while (tempC == 85.0 || tempC == (-127.0));
}

// This functions reconnects your ESP8266 to your MQTT broker
void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    if (client.connect("esp_temp_portable")) {
      Serial.println("connected");  
      // Subscribe or resubscribe to a topic
      // You can subscribe to more topics (to control more LEDs in this example)
      client.subscribe("portable/temp1");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

void setup() {
  Serial.begin(115200);
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  //Turn off wifi access point
  WiFi.mode(WIFI_STA);
 }
// ensures that you ESP is connected to wifi and mqtt broker
void loop() {
  //connect wifi if not connected
  if (WiFi.status() != WL_CONNECTED) {
    delay(1);
    setup_wifi();
    return;
}
  if (!client.connected()) {
    reconnect();
  }
  if(!client.loop())
    client.connect("esp_temp_portable");

  getTemperature();
  client.publish("portable/temp1",temperatureCString);
  delay(10000);
 }