Just use float(str), it doesn't need to catch exceptions... The issue I have seen reported several times with Arduino is that often strings are preceded (or followed?) by a space. So perhaps you can try: float f = float(trim(str));

Perhaps there is something else there.
If I type

1. String xrots = " -0.63  ";
2. float xrot = float(trim(xrots));
3. println(xrot);
4. xrots = " 0.14 ";
5. xrot = float(trim(xrots));
6. println(xrot);

in the PDE, I get the right numbers.

Your right, I just tried the same thing. Bit baffling why the full code doesn't work then.

Think I need to convert the trimmed strings to hex and see if its missing anything in the trim command, but then just plain "hex(xrots)" wont do it. Its never as simple as one line!

1. byte[] ba = xrots.getBytes();
2. for (byte b : ba) print(hex(b));
3. println();
   

I tried editing my arduino code to avoid floats, so now it transmits integers. I'm only concentrating on getting the xrots part of the program to work now.

so now the program receives a number from 0 to about 300 max.

an example transmission

string "12"
bytes (using the code in the post above) "3132"

int xrot = int(xrots);

outputs "0"

I really don't get how this is possible.

Right I've managed to get the code off of the other computer, since I can see I'm probably not going to get anywhere if I don't.

The arduino sends- (xroti and yroti are the integer values sent between 0 and 300)

Serial3.print(xroti);
Serial3.print(' ');
Serial3.println(yroti);

(goes through an Xbee to the computer, not the USB)

So a typical line is

12 30

or

12(SPACE)30(CR)(LF)

Proccesing code -

1. import processing.serial.*;
   Serial myPort;                       // The serial port
   char val;
   
   String linefeed = "000A";
   
   String xrots;
   String yrots;
   
   int yrot;
   int xrot;
   
   void setup() {
     size(500, 500);
     background(0);
     stroke(255);
     frameRate(120);
     myPort = new Serial(this, "COM4", 57600);
   }
   
   void draw() {
     background(0);
   
     if ( myPort.available() > 0) {  // If data is available,
       val = myPort.readChar();         // read it and store it in val
         if (val == 0x0a){                                 // if line feed detected, read a line
           println("line feed detected, new line");
           xrots = myPort.readStringUntil(0x20);    //read until space detected
           if (xrots != null){
             //println(xrots);
           }
           yrots = myPort.readStringUntil(0x0d);    //read until carrage feed is detected
           if (yrots != null){
             //println(yrots);
           }
        
         }
     }
   //println(val);
     if (xrots != null){
       xrots = trim(xrots);
       int xrot = int(xrots);
     }       
     if (yrots != null){
       yrots = trim(yrots);
       int yrot = int(yrots);
     }
     print("string : ");
     println(xrots);
     print("integer : ");
     println(xrot);
     if (xrots != null){
     print("bytes   : ");
     byte[] ba = xrots.getBytes();                                  //
     for (byte b : ba) print(hex(b));                               // hex tester from processing forum
     println();
     }
   }
   
   

Hopefully this is enough to figure out whats going on here.

Interesting quirk. Tried sending down serial instead of serial3, and found it sends tabs (hex 09) instead of spaces (hex 20)

result otherwise still no different though.

I wrote a new peice of code that seperated using string[] peices method, and didn't use trim at all. Found I had to add another space (using spaces to seperate) on the last item to make sure it detected the last value. Haven't worked out what was wrong overall, but I've got something that works at the moment, at least. Thanks for the help so far guys.