Exit Status 1: expected primary-expression before ',' token

Using Arduino Programming Questions
#1

Hi! My project is about DHT22 and LCD Screen 1602A.
Where did I do wrong in the code?

Below is the code I’m using

/*     LCD DHT-22 Temp & Humidity Sensor
    www.ardumotive.com // Project Corner
        Vasilakis Michalis - date: 18/2/2015
    Many thanks to Rob Tillaart for DHT library!  */

//Libraries
#include <Adafruit_Sensor.h>
#include <DHT.h>
#include <DHT_U.h>
#include <LiquidCrystal.h>

// initialize the lcd library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
//DHT pin to arduino pin 6
#define dhtPin
#define dht22
#define DHTTYPE dht22
DHT dht (dhtPin , DHTTYPE)
float temp = dht.readTemperature();
const int dhtPin = 6;

//Variables
int chk;
float hum;
float temp;
void setup()
{
    lcd.begin(16,2);
}

void loop()
{
    // READ DATA
    chk = dht.read22(dhtPin);
    hum = dht.humidity;
    temp= dht.temperature;
    // DISPLAY DATA
    lcd.setCursor(0,0);
    lcd.print("Temp: ");
    lcd.print(temp,1);
    lcd.print(char(223)); // Print degree symbol
    lcd.print("C");
    lcd.setCursor(0,1); // Change lcd line...
    lcd.print("Humidity: ");
    lcd.print(hum,0);
    lcd.print("%");
    delay(2000); //Refresh every 2 sec.
}

and error message below:

Arduino: 1.8.7 (Windows Store 1.8.15.0) (Windows 10), Board: "Arduino/Genuino Uno"

dht22lcd:18:17: error: expected primary-expression before ',' token

 DHT dht (dhtPin , DHTTYPE)

                 ^

dht22lcd:18:26: error: expected primary-expression before ')' token

 DHT dht (dhtPin , DHTTYPE)

                          ^

dht22lcd:19:1: error: expected ',' or ';' before 'float'

 float temp = dht.readTemperature();

 ^

dht22lcd:20:18: error: expected unqualified-id before '=' token

 const int dhtPin = 6;

                  ^

C:\Users\Lenovo\Downloads\dht22lcd\dht22lcd.ino: In function 'void loop()':

dht22lcd:34:15: error: 'class DHT' has no member named 'read22'

     chk = dht.read22(dhtPin);

               ^

dht22lcd:35:15: error: 'class DHT' has no member named 'humidity'

     hum = dht.humidity;

               ^

dht22lcd:36:15: error: 'class DHT' has no member named 'temperature'

     temp= dht.temperature;

               ^

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

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

Thanks in advance!

#2

You haven't given dhtPin a number; try something like

#define dhtPin 6
#3

Thanks! That solves one problem.

What about: expected primary-expression before ‘)’ token and also other errors?
What should I do to the code?

Error Code:

Arduino: 1.8.7 (Windows Store 1.8.15.0) (Windows 10), Board: "Arduino/Genuino Uno"

dht22lcd:18:26: error: expected primary-expression before ')' token

 DHT dht (dhtPin , DHTTYPE);

                          ^

dht22lcd:15:16: error: expected unqualified-id before numeric constant

 #define dhtPin 6

                ^

C:\Users\Lenovo\Downloads\dht22lcd\dht22lcd.ino:19:11: note: in expansion of macro 'dhtPin'

 const int dhtPin = 6;

           ^

C:\Users\Lenovo\Downloads\dht22lcd\dht22lcd.ino: In function 'void loop()':

dht22lcd:35:15: error: 'class DHT' has no member named 'read22'

     chk = dht.read22(dhtPin);

               ^

dht22lcd:36:15: error: 'class DHT' has no member named 'humidity'

     hum = dht.humidity;

               ^

dht22lcd:37:15: error: 'class DHT' has no member named 'temperature'

     temp= dht.temperature;

               ^

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

Renewed code:

/*     LCD DHT-22 Temp & Humidity Sensor
    www.ardumotive.com // Project Corner
        Vasilakis Michalis - date: 18/2/2015
    Many thanks to Rob Tillaart for DHT library!  */

//Libraries
#include <Adafruit_Sensor.h>
#include <DHT.h>
#include <DHT_U.h>
#include <LiquidCrystal.h>

// initialize the lcd library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
//DHT pin to arduino pin 6
#define dhtPin 6
#define dht22
#define DHTTYPE dht22
DHT dht (dhtPin , DHTTYPE);
const int dhtPin = 6;

//Variables
int chk;
float hum;
float temp = dht.readTemperature();


void setup()
{
    lcd.begin(16,2);
}

void loop()
{
    // READ DATA
    chk = dht.read22(dhtPin);
    hum = dht.humidity;
    temp= dht.temperature;
    // DISPLAY DATA
    lcd.setCursor(0,0);
    lcd.print("Temp: ");
    lcd.print(temp,1);
    lcd.print(char(223)); // Print degree symbol
    lcd.print("C");
    lcd.setCursor(0,1); // Change lcd line...
    lcd.print("Humidity: ");
    lcd.print(hum,0);
    lcd.print("%");
    delay(2000); //Refresh every 2 sec.
}
#4 
#define dht22
#define DHTTYPE dht22

What do you expect the value of DHTTYPE to be after these two macro definitions?

#5

I missed the const int dhtPin, sorry.

You need either thar or the #define; and before you use the constructor (DHT dht (dhtPin , DHTTYPE);.

On a cell phone so it's difficult to spot further mistakes.

#6

gfvalvo:
What do you expect the value of DHTTYPE to be after these two macro definitions?

So what should I do to the code?

#7 
#include <Adafruit_Sensor.h>
#include <DHT.h>
#include <DHT_U.h>

Many thanks to Rob Tillaart for DHT library!

These are two different libaries for the sensor.

You are using syntax from the Tillart library but have #included the Adafruit libary.

You need to review which library you want to use. Look at the library examples, and get the code syntax and library used to match.

#8

I tried to use the Rob Tillaart but it keeps telling me: Specified folder/zip file does not contain a valid library.

#9

I tried to use the Rob Tillaart but it keeps telling me: Specified folder/zip file does not contain a valid library.

Where are you trying to download a zip version of this library from?

The library is small, and you can also manually copy the .h , .cpp and examples files from github into a text editor. Save them as .cpp , .h files and .ino files into folder you create in your user libraries.

#10

I have downloaded it from github.com and it appears at "Arduino-master" in my download file as a zip file
But when I tried to Add .zip library it said that Specified folder/zip file does not contain a valid library.

cattledog:
The library is small, and you can also manually copy the .h , .cpp and examples files from github into a text editor. Save them as .cpp , .h files and .ino files into folder you create in your user libraries.

Arduino/libraries/DHTlib at master · RobTillaart/Arduino · GitHub

What do you mean by manually copy the .h, .cpp and examples files from github into a text editor?

#11

I have downloaded it from github.com and it appears at "Arduino-master" in my download file as a zip file
But when I tried to Add .zip library it said that Specified folder/zip file does not contain a valid library.

Here's a process I followed. In downloads, double click and navigate through the "Arduino-master" untill you get to a level called "libraries." You will find "DHTlib" there. Make a copy and paste it on the destop.

Then, when you use the Add.ZIPLibrary use "look in" to select the desktop, and then click on DHTlib. It will show in the file name bar and will added when you click "open".

#12

Thank you so much cattledog and others who helped me!
Finally the code is able to be compiled :slight_smile:
Again, thanks for your guidance!

#13