Temperature control using a DHT11

Question

I am trying to do a project on temperature control and found an example but cannot get the code to work. I have read forums and tried to fix the issue which is below the code.

Code:

#include<DHT.h>      // Including library for dht
#include<LiquidCrystal.h>
LiquidCrystal lcd(2, 3, 4, 5, 6, 7);
#define dht11dpin 12
DHT11;
#define pwm 9
#byte degree[8] =
{
  0b00011,
  0b00011,
  0b00000,
  0b00000,
  0b00000,
  0b00000,
  0b00000,
  0b00000
};


#void setup()
{
  lcd.begin(16, 2);
  lcd.createChar(1, degree);
  lcd.clear();
  lcd.print("   Fan Speed  ");
  lcd.setCursor(0, 1);
  lcd.print("  Controlling ");
  delay(2000);
  analogWrite(pwm, 255);
  lcd.clear();
  lcd.print("Circuit Digest ");
  delay(2000);
}


void loop()
  DHT11.read(DHT11pin);
  int temp = DHT11.temperature;
  lcd.setCursor(0, 0);
  lcd.print("Temperature:");
  lcd.print(temp);   // Printing temperature on LCD
  lcd.write(1);
  lcd.print("C");
  lcd.setCursor(0, 1);
  if (temp < 26 )
  {
    analogWrite(9, 0);
    lcd.print("Fan OFF            ");
    delay(100);
  }
  else if (temp == 26)
  {
    analogWrite(pwm, 51);
    lcd.print("Fan Speed: 20%   ");
    delay(100);
  }
  else if (temp == 27)
  {
    analogWrite(pwm, 102);
    lcd.print("Fan Speed: 40%   ");
    delay(100);
  }
  else if (temp == 28)
  {
    analogWrite(pwm, 153);
    lcd.print("Fan Speed: 60%   ");
    delay(100);
  }
  else if (temp == 29)
  {
    analogWrite(pwm, 204);
    lcd.print("Fan Speed: 80%    ");
    delay(100);
  }
  else if (temp > 29)
  {
    analogWrite(pwm, 255);
    lcd.print("Fan Speed: 100%   ");
    delay(100);
  }
  delay(3000);
}

Error:

In file included from C:\Users\neilb\Documents\Arduino\sketch_jan20b\sketch_jan20b.ino:2:0:
C:\Users\neilb\Documents\Arduino\libraries\DHT_sensor_library/DHT.h:32:15: error: expected unqualified-id before numeric constant
 #define DHT11 11
               ^
C:\Users\neilb\Documents\Arduino\sketch_jan20b\sketch_jan20b.ino:6:1: note: in expansion of macro 'DHT11'
 DHT11;
 ^
C:\Users\neilb\Documents\Arduino\libraries\DHT_sensor_library/DHT.h:32:15: error: expected initializer before numeric constant
 #define DHT11 11
               ^
C:\Users\neilb\Documents\Arduino\sketch_jan20b\sketch_jan20b.ino:35:1: note: in expansion of macro 'DHT11'
 DHT11.read(DHT11pin);
 ^
sketch_jan20b:36: error: request for member 'temperature' in '11', which is of non-class type 'int'
 int temp=DHT11.temperature;
                ^
sketch_jan20b:37: error: 'lcd' does not name a type
   lcd.setCursor(0,0);
   ^
sketch_jan20b:38: error: 'lcd' does not name a type
   lcd.print("Temperature:");
   ^
sketch_jan20b:39: error: 'lcd' does not name a type
   lcd.print(temp);   // Printing temperature on LCD
   ^
sketch_jan20b:40: error: 'lcd' does not name a type
   lcd.write(1);
   ^
sketch_jan20b:41: error: 'lcd' does not name a type
   lcd.print("C");
   ^
sketch_jan20b:42: error: 'lcd' does not name a type
   lcd.setCursor(0,1);
   ^
sketch_jan20b:43: error: expected unqualified-id before 'if'
   if(temp <26 )
   ^
sketch_jan20b:50: error: expected unqualified-id before 'else'
     else if(temp==26)
     ^
sketch_jan20b:57: error: expected unqualified-id before 'else'
      else if(temp==27)
      ^
sketch_jan20b:64: error: expected unqualified-id before 'else'
      else if(temp==28)
      ^
sketch_jan20b:71: error: expected unqualified-id before 'else'
     else if(temp==29)
     ^
sketch_jan20b:77: error: expected unqualified-id before 'else'
      else if(temp>29)
      ^
sketch_jan20b:83: error: expected constructor, destructor, or type conversion before '(' token
   delay(3000);
        ^
sketch_jan20b:84: error: expected declaration before '}' token
 }
 ^
exit status 1
request for member 'temperature' in '11', which is of non-class type 

Answer 1

It's a bit hard to see, but

DHT11;  

does not look like a correct statement, assuming DHT11 is a class (not a define like shown) it should be something like

DHT11 dht; 

where dht is an instance and you can use that.

Than in

DHT11.read(DHT11pin);

you should replace it by

dht.read(DHT11pin);