string to float

s2jesse

Is there a simple object etc or a simple meathod to do· a string to float...
I've used fromString etc but it doenst seem to work with my float math

As a simple example im taking the knots string·from my gps·and converting it to mph but i cant seem to get a float im guesing it is only converting it out to an int.

Thanks Sorry for my continued newbness...

Jesse
·

Ale

Will be a good idea if you can get back the number converted and compare it with what scanf or other simular function will produce. An example of the numbers your gps module gives could also help to determine why (if) it is failing.

grasshopper

Try the string to float object. The new one works pretty good.

s2jesse

I·searched the obex for string to float i didnt see the object you speak of.. am i blind?
Thanks
Jesse

ratronic

It's called "FloatString" in the obex.

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Fix it, if it ain't broke·

D Rat


Dave Ratcliff· N6YEE

s2jesse

From what i can tell that does the opposite of what "think" i need heres an example...

'===== Speed MPH =====
    term.out($0D)                                     'line break   
    term.str(string("MPH:"))
    term.str(sense.mph) 

PUB mph | k, m
  k := gps.speed     
  m := fm.FMul(k, 1.1508)
     
  return fs.FloatToFormat(m,6,2)

k is a string like 0.14 (ive checked it)
m is always· coming through as "··· 0.0"

if i manually set k to something like··· ·k := 4.5 it works
the result works.· Im having hard time grasping the simple basics of how these variables work. i dont get how the prop stores a float in a long vs a string etc.






Post Edited (s2jesse) : 7/23/2008 5:13:27 AM GMT

Leon

It uses 32-bit IEEE floating-point format:

http://en.wikipedia.org/wiki/IEEE_754

Leon

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s2jesse

I see thanks

Hrm well it is clearer to me that I do need to convert the string the gps object is returning to a float.
Ive used numbers.spin to convert to ints etc but i just don't see any usermade objects that will convert to float..

Any last insight before I dive in and poorly attempt to reinvent the wheel. [noparse]:)[/noparse]

Ariba

Hello Jesse

here is a simple String to Float conversion:

PUB StrToFloat(strptr) : flt | int,exp,sign
  int := exp := sign := 0
  repeat strsize(strptr)                   'string to integer
    case byte[noparse][[/noparse]strptr]
      "-":      sign~~
      ".":      exp := 1
      "0".."9": int := int*10 + byte[noparse][[/noparse]strptr] - "0"
                if exp
                  exp++                    'count dec places
      other:    quit
    strptr++
  if sign
    int := -int
  flt := f.FFloat(int)
  if exp
    repeat exp-1
      flt := f.FDiv(flt,10.0)              'adjust float

This function supports no scientific format (i.e. 1.23e6), and max 9 decimal digits in the string.

Attached is a little Demo.

Andy

grasshopper

Perhaps you can post some more of the code so we can see the problem. Also you have to make sure that both numbers are the same data type i.e. "floating point" to multiply them together.

Post Edited (grasshopper) : 7/23/2008 5:05:19 PM GMT

s2jesse

grasshopper,,
basically that was the problem i needed to know how to make them both floating point... hence the question how do i convert a string to a float... but i think ariba has graciously supplied me with the answer / code... i have yet to try it out but when i can ill give it a shot... thanks all

s2jesse

Ariba

yep thanks worked like a charm!