I am trying to store temperature data in a variable, so that I can use it for making a JSON object, but the problem is, that when I try to store the temperature in a variable, it prints out the wrong value. I'm using a DHT11 temperature/humidity sensor and a library for calculating the temperature.

Serial.print("Temperature (°C): ");
Serial.println((float)DHT11.temperature, DEC);
int temp1 = ((float)DHT11.temperature, DEC);

These 4 lines is printing out this:

Temperature (°C): 23.0000000000

The first one is correct, but the second line should also be saying "23". I have tried only loading the data in once with the library, as in outcommenting one line, but that does not work. It's like I have some syntax wrong, but I can't figure out what.

1 Answer 1


This line:

int temp1 = ((float)DHT11.temperature, DEC);

casts DHT11.temperature to an float, throws away the value, then assigns DEC to temp1. That is not what you want.

int temp1 = DHT11.temperature;
  • Thank you so much. This fixed it straight away. I knew it was just some stupid syntax that I was doing wrong, but I just couldn't figure out what. Thnx.
    – Djensen
    Commented Jan 20, 2015 at 15:21
  • 1
    For extra reading: en.wikipedia.org/wiki/Comma_operator
    – Omer
    Commented Jan 20, 2015 at 23:59

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