exit status 1 expected primary-expression before '[' token

//BY TRAN TIEN
#include <DHT.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27,16,2);

const int DHTPIN = 2;
const int DHTTYPE = DHT11;
const int QUAT = A0;
const int DEN_SANG =A1;
DHT dht(DHTPIN, DHTTYPE,QUAT,DEN);

byte degree[8] = {
0B01110,
0B01010,
0B01110,
0B00000,
0B00000,
0B00000,
0B00000,
0B00000
};
byte HNhietDo,LNhietDo;
byte NhietDoMin=19,NhietDoMax=21;
void setup() {
pinMode(QUAT,OUTPUT);
pinMode(DEN,OUTPUT);
digitalWrite(QUAT,0);
digitalWrite(DEN,0);
lcd.init();
lcd.backlight();

lcd.print("Nhiet DO: ");
lcd.setCursor(0,1);
lcd.print("DO AM: ");

lcd.createChar(1, degree);

dht.begin();
}

void loop() {
float h = dht.readHumidity();
float t = dht.readTemperature();
if(HNhietDo<NhietDoMin)
{
digitalWrite(DEN,1);
digitalWrite(QUAT,0);
}
else if(HNhietDo>=NhietDoMax)
{
digitalWrite(DEN,0);
digitalWrite(QUAT,1);
}
if (isnan(t) || isnan(h)) {
}
else {
lcd.setCursor(10,0);
lcd.print(round(t));
lcd.print(" ");
lcd.write(1);
lcd.print(ā€œCā€);

lcd.setCursor(10,1);
lcd.print(round(h));
lcd.print(" %");
}
}

Nice code. Please post it correctly. Please ask whatever question you have. Just the code by itself doesn't say much. If you have an error then post the error message.

DHT dht(DHTPIN, DHTTYPE, QUAT, DEN);

Where in the code is DEN declared ?