[Tutor] Re: Please critique my temperature_conversion.py (original) (raw)

Andrei project5 at redrival.net
Mon Jul 12 17:34:22 CEST 2004

Dick Moores <rdm rcblue.com> writes:

Exception handling is new to me, and I haven't succeeded here yet, as you can see.

I think you've gone a bit overboard on the exception handling :). All you need to check is three things:

  1. there is input
  2. the temperature unit is known
  3. the input is a number

Raw outline, doesn't use your variable names since it's just for demonstration purposes (continue breaks the current iteration and starts again at the top of the loop):

while True:
temperature = raw_input('Temp:').strip()

# make sure there is input at all
try:
    temp_unit = temperature[-1].upper()
    temp_value = temperature[:-1].strip()
except: # input is too short
    print "Wrong input! Specify a value followed by a unit."
    continue

# make sure we know the unit
if not (temp_unit in ['F', 'C']):
    print "Unknown unit (%s)." % temp_unit
    continue

# make sure the value is a number
try:
    temp_value = float(temp_value)
except:
    print "The value you specified (%s) is not a number!" % temp_value
    continue
    
print "OK"

# Here comes the code which performs the conversion. You don't
# have to do any  more try-excepts here, because you're sure
# that your input is valid.

And how to provide a smooth exit from the program? I experimented with the exception that Ctrl+C raises, but doing this seems to make my

Ctrl+Break should terminate it. Or you could build in an option to specify e.g. "X" to exit. You then check if the (stripped and uppercased) input is X and if that is the case, use break to terminate the loop (and therefore stop the program). I'd recommend checking for more than one exit command (e.g. 'quit', 'exit', 'stop', 'q' and 'x') so the user can press whatever seems logical to her and gets the desired result - the program terminates.

No command line execution yet.

Hint: sys.argv. It's very handy for this type of programs.

Yours,

Andrei

More information about the Tutor mailing list