this code for sensors DHT22 (temperature and humidity) and for gaz sensor

Code

//Libraries

#include <DHT.h>

//Constants
#define DHTPIN 2     // what pin we're connected to
#define DHTTYPE DHT22   // DHT 22  (AM2302)
DHT dht(DHTPIN, DHTTYPE); //// Initialize DHT sensor for normal 16mhz Arduino


//Variables
int chk;
float hum;  //Stores humidity value
float temp; //Stores temperature value
const int gasPin = A0; //GAS sensor output pin to Arduino analog A0 pin


void setup()
{
    Serial.begin(9600);  //Initialize serial port - 9600 bps
  dht.begin();

}


void loop()
{
  Serial.println(analogRead(gasPin));
  delay(1000); // Print value every 1 sec.
  
    //Read data and store it to variables hum and temp
    hum = dht.readHumidity();
    temp= dht.readTemperature();
    //Print temp and humidity values to serial monitor
    Serial.print("Humidity: ");
    Serial.print(hum);
    Serial.print(" %, Temp: ");
    Serial.print(temp);
    Serial.println(" Celsius");
    delay(2000); //Delay 2 sec.

  
}