Integer to String

Projects Programming
1

I am working on a project that passes a string from an Arduino Uno to MIT App Inventor via an HC-05 Bluetooth thingy.

The Arduino does a routine to create several integers (weight_FL, weight_FR, weight_RL and weight_RR). I then take these integers and create a string for each. I then join the separate strings into one with a delimeter between them.

StringFL = String(weight_FL,0);
  StringFR = String(weight_FR,0);
  StringRL = String(weight_RL,0);
  StringRR = String(weight_RR,0);
  StringDataSent = String(StringFL + "/" + StringFR + "/" + StringRL + "/" + StringRR);

The AI2 is receiving the string but says it cannot use the string/number in mathematical caluclations. I believe this is due to each number being preceeded with a space (I have been told elsewhere that AI2 is smart enough to auto convert a text number to a number). I have looked in the serial monitor and there is definitely a space being added when first 4 strings are created.

Previously I used

StringFL = String(weight_FL);

but this resulted in "0.00" being sent even though I had previously converted the value to an integer. Originally I thought the ".00" part was causing this issue.

I think I need to fix this issue in the Arduino code so that either the ".00" is not added to the end or no space is added at the beginning but I have drawn a blank even though I am sure it is a simple solution. Can you assist??

2

Simple answer, skip the useless String and go for string :slight_smile: Is slow and takes a lot of memory for a simple task.

Just don't concatenate it first, just send it the way you want it

  Serial.print(weight_FL);
  Serial.print('/');
  Serial.print(weight_FR);
  Serial.print('/');
  Serial.print(weight_RL);
  Serial.print('/');
  Serial.print(weight_RR);
3

Wow super fast response!!

I tried the code you suggested and all that does is to go back to adding ".00" onto the end of the strings. AI2 still cannot perform maths on those strings.

4

If your weight variables are floats, you will get the decimals for free :smiley: It's the way Serial.print works (and probably the String class as well);

To get rid of it, the first line posted by septillion will be

Serial.print((int)weight_FL);
5

If you get .00 then your variables are not int like you said :wink: Or change them to real int (float is slow and isn't needed for 99% of the calculations on the forum anyway). Or use Serial.print(weight_FL, 0) to specify you want 0 decimal places.

6

OK I am a complete nob. I thought they were integers but septillion made me question it. I had a routine that ensured they rounded to the nearest integer (I think the int command just cuts off the decimals without rounding up?) but I had not actually set them as integers. Stupidity just cost me 3 hours!!!

I assume using septillions code rather than my clumsy Strings would run faster??

Thanks for the help.

7

Yep it does. Sting has a lot of (memory) overhead.

Btw, rounding to the nearest int instead of flooring it is easy by just adding 0,5. Or, don't use float at all :slight_smile:

PS Things like this happen when you don't follow forum rules and just post a snipped. :wink: