Temp was not declared in this scope when getting values from bool - c++

Question

Hello I wanted to change some voids to bools and I am a little lost. I understand if you write a void or a bool and want to add the values to the next void you just insert the code to add the previous function
I don't know how to explain it I am just gonna tell you what I want to do:
created a new bool getValues and added all the value getting code from the sensors then I wanted to send the data to void loop that will send the data through mqqt to raspberry.
I understand that bool is for true and false. but I don't really understand the etiquette of using it
so the problem I am getting 'temp' was not declared in this scope at the void loop function
I highlighted the function with // where I get the error it's almost at the bottom
#include "DHT.h"
#include <WiFi.h>
#define DHTPIN 25 // Digital pin connected to the DHT sensor
#define DHTTYPE DHT11 // DHT 11
//MQTT Setup Start
#include <PubSubClient.h>
#define mqtt_server "192.168.1.210"
WiFiClient espClient;
PubSubClient client(espClient);
#define mqttlightReadingpercent "greenHouse/light"
#define mqttsoilmoisturepercent "greenHouse/soil"
#define mqtttemp "greenHouse/temp"
#define mqtthum "greenHouse/hum"
//MQTT Setup End
const char* ssid = "Cgates_E031F1"; // ESP32 and ESP8266 uses 2.4GHZ wifi only
const char* password = "60E541C32F";
DHT dht(DHTPIN, DHTTYPE);
const byte lightPin = 33;
int lightReading;
int lightReadingpercent=0;
//const int RELAY_PIN = 15; // the Arduino pin, which connects to the IN pin of relay
// soil moisture
const int AirValue = 4095; //you need to replace this value with Value_1
const int WaterValue = 2200; //you need to replace this value with Value_2
const int SensorPin = 32;
int soilMoistureValue = 0;
int soilmoisturepercent=0;
const int Lightvalue = 0;
const int Darkvalue = 4095;
unsigned long millisNow = 0; //for delay purposes
unsigned int sendDelay = 20000; //delay before sending sensor info via MQTT
void setup() {
// put your setup code here, to run once:
Serial.begin(9600);
Serial.println();
// begin Wifi connect
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.mode(WIFI_STA);
WiFi.disconnect();
delay(2000);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
//end Wifi connect
client.setServer(mqtt_server, 1883);
// pinMode(RELAY_PIN, OUTPUT);//relay
pinMode(lightPin, INPUT);
pinMode(SensorPin, INPUT);
Serial.println(F("DHTxx test!")); //dht
;
dht.begin();
}
void reconnect() {
// Loop until we're reconnected
int counter = 0;
while (!client.connected()) {
if (counter == 5) {
ESP.restart();
}
counter+=1;
Serial.print("Attempting MQTT connection...");
// Attempt to connect
if (client.connect("greenHouseController")) {
Serial.println("connected");
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}
bool getValues() {
lightReading = analogRead(lightPin); //0-4095 12bit -- esp8266 10bit 0-1023 -- arduino 8bit 0-254
Serial.print("Light reading = ");
lightReadingpercent = map(lightReading, Darkvalue, Lightvalue, 0, 100 );
Serial.print(lightReadingpercent);
Serial.println(" %");
Serial.println();
soilMoistureValue = analogRead(SensorPin); //put Sensor insert into soil
soilmoisturepercent = map(soilMoistureValue, AirValue, WaterValue, 0, 100);
if (soilmoisturepercent > 100) {
Serial.println("Soil moisture ");
Serial.println("100 %");
delay(500);
}
else if(soilmoisturepercent <0) {
Serial.println("Soil moisture ");
Serial.println("0 %");
delay(500);
}
else if (soilmoisturepercent >=0 && soilmoisturepercent <= 100) {
Serial.println("Soil moisture "); //go to next line
Serial.print(soilmoisturepercent);
Serial.println("%");
delay(500); // soil end
}
delay(500);
// Reading temperature or humidity takes about 250 milliseconds!
// Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
float hum = dht.readHumidity();
// Read temperature as Celsius (the default)
float temp = dht.readTemperature();
// Read temperature as Fahrenheit (isFahrenheit = true)
float f = dht.readTemperature(true);
// Check if any reads failed and exit early (to try again).
if (isnan(hum) || isnan(temp) || isnan(f)) {
Serial.println(F("Failed to read from DHT sensor!"));
return 1;
}
// Compute heat index in Fahrenheit (the default)
float hif = dht.computeHeatIndex(f, hum);
// Compute heat index in Celsius (isFahreheit = false)
float hic = dht.computeHeatIndex(temp, hum, false);
Serial.print(F(" Humidity: "));
Serial.print(hum);
Serial.print(F("% Temperature: "));
Serial.print(temp);
Serial.print(F("C "));
Serial.print(f);
Serial.print(F("F Heat index: "));
Serial.print(hic);
Serial.print(F("C "));
Serial.print(hif);
Serial.println(F("F"));
delay(500); //wait 0.5seconds
}
void loop() {
if (!client.connected()) {
reconnect();
}
if (millis() > millisNow + sendDelay) {
if (getValues()) {
client.publish(mqttlightReadingpercent, String(lightReadingpercent).c_str(),true);
client.publish(mqttsoilmoisturepercent, String(soilmoisturepercent).c_str(),true);
client.publish(mqtttemp, String(temp).c_str(),true); // the problem is here
client.publish(mqtthum, String(hum).c_str(),true);
millisNow = millis();
}
}
client.loop();
/*if (moisture_level < 10) {
digitalWrite(RELAY_PIN, HIGH); // turn on pump 5 seconds
delay(5000);
}
else {
digitalWrite(RELAY_PIN, LOW); // turn off pump 5 seconds
delay(5000);
}*/
}

Answer 1

By moving your code to getValues, you also changed the scope in which your temp variable exists in. Variables are not automatically globally available. If you declare a variable inside a function (which getValues is), it's only available in this function.
When you try to access the temp variable in your loop function, the compiler rightly tells you, that there is no such variable available.
You could solve the problem by declaring temp as a global variable, which you would do by adding float temp = 0 up on top where you also declare variables like soilMoistureValue. Make sure not to redeclare the variable in getValues then, so instead of declaring like so float temp = dht.readTemperature(); you just assign a new value like so temp = dht.readTemperature();
A quick note on your first paragraph: The voids and bools how you call it, define the return type of a function. If your function does not return anything, you define it as void. If it returns a boolean value (so true or false), you define so bool. In the case of your getValues function, since it does not return anything, it should be void getValues.