DHT11 float and string question

Archive
1

Hello,
I am trying to do an if statement. I am getting a error [quote]Operator ‘<’ cannot be applied to operands of type ‘string’ and 'string[/quote] How do I use the < operator in this case?
Thanks,
I am a beginner.
Sensor Page: http://code.tinyclr.com/project/289/dht11---temperature-and-humidity-sensor/


namespace Sensor Test
{
    public class Program
    {

        public static void Main()
        {
            DHT11 MyDHT11 = new DHT11((Cpu.Pin)FEZ_Pin.Digital.Di6, (Cpu.Pin)FEZ_Pin.Digital.Di7);
            if (MyDHT11.Humidity.ToString() < "26") 

            }
        }
    }
2

You need to convert value to an int and then check if it is less then 26.

3

To convert:

int x = int.Parse(MyDHT11.Humidity.ToString());

Note 1: This code doesn’t do error checking (like if the Humidity value == “too high!!”).

For that look into int.TryParse().

Note 2: If MyDHT11.Humidity is already a string value, then you don’t need to do .ToString() again.

4

Thank You,

5

Sorry, I am reciving a error

Here is the code


DHT11 MyDHT11 = new DHT11((Cpu.Pin)FEZ_Pin.Digital.Di6, (Cpu.Pin)FEZ_Pin.Digital.Di7);

            while (true)
            {
                if (MyDHT11.ReadSensor())
                {
                    int x = int.Parse(MyDHT11.Humidity.ToString());
                    if (x < "26")                 
                        Debug.Print("The humidity is less than 26");                  
                    else 
                        Debug.Print("The humidity is more than 26");
                }
                else 
                    Debug.Print("DHT11 Error : " + MyDHT11.LastError);

Thanks, :slight_smile:

6

you’ve converted the humidity back to an integer, but you’re still comparing it to “26” which is a string.

Remove the quotes and you will be fine.

if (x < 26)
7

Thank You,
It works!

8

Guys,

why all the fuzz with that conversion to int’s or strings??

The driver returns a float so you can just do:


DHT11 MyDHT11 = new DHT11((Cpu.Pin)FEZ_Pin.Digital.Di6, (Cpu.Pin)FEZ_Pin.Digital.Di7);
 
            while (true)
            {
                if (MyDHT11.ReadSensor())
                {
                    if (MyDHT11.Humidity < 26f)                 
                        Debug.Print("The humidity is less than 26");                  
                    else 
                        Debug.Print("The humidity is more than 26");
                }
                else 
                    Debug.Print("DHT11 Error : " + MyDHT11.LastError);
9

Doh! :wall:

10

Thanks,

11

actually, let’s blame Gus. I think he must have been iPhoning and said “yes” when asked was it a string - which got us to where we are now :slight_smile: :slight_smile:

12

How can I make this up to yo guys? What about another FEZ?

13

announcement inbound? :o

14

I finally, after many long hours, got the four LEDs fading from one to another in a kind-of circle on my STM32F4-Discovery board.

Wow, it really makes you appreciate NETMF and especially GHI’s support and documentation!

So, Gus, to answer your question, yes, another FEZ will make it all better.

15

You got the port working on Discovery?

16

Haha, no, I wish. I’m just working in C/ASM in Atollic’s free version.

17

I am learning a lot about porting kit and that board in particular. I like it.