Stuck on simple python prob

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February 18th, 2013, 11:04 AM

dkoleary

Registered User

Join Date: Feb 2013

Posts: 11

Time spent in forums: 4 h 45 m 47 sec
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Stuck on simple python prob

Hey;

I'm a recoverying perl programmer trying to pick up python as part of my current gig. I went out and found some 'practice' problems on the web which don't supply answers. Theoretically, shouldn't need 'em, this one should be simple, but it's got me stumped.

Short version: temperature conversion between celsius and farenheight

Here's the code:

Code:

#!/usr/bin/python

def c2f(n):
   """Converts Celsius to Farenhieht"""
   tf=(9/5 * n) + 32
   return tf

def f2c(n):
   """Converts Farenheit to Celsius"""
   print "N: " + n
   tc = (5/9) * (int(n)-32)  ## problem seems to be here
   print "TC: %5.2f" % (tc,)
   return tc

T = 'abc'
while not T.isdigit():
   T = raw_input("Enter a temperature: ")

C = 'abc'
while C.upper() not in ['C', 'F']:
   C = raw_input("Convert to (F)arenheight or (C)elsius: ")

if C.upper() == 'C':
   n = f2c(T)
else:
   n = c2f(T)

print "Converted: %3d" % (n,)

When I run it, I get:

Code:

$ ./temp_converter.py
Enter a temperature: 80
Convert to (F)arenheight or (C)elsius: c
N: 80
TC:   0.00

I'm suspecting some type of integer/string/float conversion issue; however, I've tried all three in the print statement to no avail.

I know the c2f function is borked; I figure I can get that fixed once I figure out what's up with the f2c.

I've apparently missed some fairly basic concept. Can someone point it out to me?

Thanks.

February 18th, 2013, 11:28 AM

b49P23TIvg

Contributing User

Join Date: Aug 2011

Posts: 3,379

Time spent in forums: 1 Month 2 Weeks 3 Days 13 h 3 m 20 sec
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5/9 is zero in python2.
float(5)/9 is not zero in python2

Code:

#!/usr/bin/python

from __future__ import division  ############ use this

def c2f(n):
   """Converts Celsius to Farenhieht"""
   tf=(9/5 * n) + 32
   return tf

def f2c(n):
   """Converts Farenheit to Celsius"""
   tc = (5/9) * (n-32)  ## problem seems to be here
   return tc

T = 'abc'
while not T.isdigit():
   T = raw_input("Enter a temperature: ")

T = float(T) # avoid duplicate code
   
C = 'abc'
while C.upper() not in 'CF':
   C = raw_input("Convert to (F)ahrenheit or (C)elsius: ")

if C.upper() == 'C':
   n = f2c(T)
else:
   n = c2f(T)

print "Converted: %3d" % (n,)

__________________
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February 18th, 2013, 02:24 PM

dkoleary

Registered User

Join Date: Feb 2013

Posts: 11

Time spent in forums: 4 h 45 m 47 sec
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Quote:

Originally Posted by b49P23TIvg

5/9 is zero in python2.
float(5)/9 is not zero in python2

Ah, so typecasting. eh, it's a form of conversion so I wasn't far off, I guess.

Thanks very much for the pointer. Hopefully, I won't run face first into that too many more times before it sinks in.

Doug

Stuck on simple python prob

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