Converting a String to Long in Processing

Using Arduino Interfacing w/ Software on the Computer
1

Hi guys.

I've done some research before posting this but can't get an answer that makes sense.

I'm using Processing 2.2.1 to read serial data from a Uno and write it to a file. All good so far, it's working as expected. The data supplied from the usb port "appears" numeric when read off the A/D converter 0-1023. But it's not really numeric, it's a string.

I can understand why because of "sensorValue = myPort.readString();" so I guess reading from the serial port is considered as a string in any programming language?.

Regardless, I need to convert it to numbers so I can do some basic math calculations.

Help would be appreciated.

Cheers.

2

so I guess reading from the serial port is considered as a string in any programming language?.

No. Reading from the serial port using readString() and expecting something other than a string hardly makes sense.

Regardless, I need to convert it to numbers so I can do some basic math calculations.

Why do you (think you) need to convert the string representation of a value between 0 and 1023 to a long?

Processing makes it simple to convert a string to an int.
https://www.processing.org/discourse/beta/num_1173249138.html

3

Ok thanks Paul,

Yes, I did realise readString() was going to return a string but there didn't appear to be any other option. According to the reference, read() returns a number between 0-255.

In fact, I will ultimately need to read 0-32767 (15 bit). I was under the impression that the type int was 0-255, therefore I thought I needed long. Although I have now read from the reference "Datatype for integers, numbers without a decimal point. Integers can be as large as 2,147,483,647 and as low as -2,147,483,648." ???

Which has now confused me even more.

Thanks for the link. So the code would look something like this?:

string sensorValue;
sensorValue = myPort.readString();
int sensorValueNumber = Integer.parseInt(sensorValue);
println(sensorValueNumber);

4

So the code would look something like this?:

Yes, but it looks weird separating the declaration of the variable from the valuation of the variable.

string sensorValue = myPort.readString();

looks better to me.

The name is lousy, though, since the "value" is a string.

string valStg = myPort.readString();
int sensorValue = Integer.parseInt(valStg);

is what I would do.

5

Ah yes - that does make it a cleaner.

Thanks for your help Paul, I'll try this out when I get home from work.

Cheers.

btw. forgot to ask: Is it correct that the int range is 2,147,483,647 and as low as -2,147,483,648?
I guess there's only one way to find out for sure :slight_smile: