[Tutor] Declare empty string variable?

[Bob Gailer]

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### Decimal to Binary Conversion
 > deci=input("Decimal? --> ")
 > dual= <--- declaration
 > ...
 > while deci>0:
 >     dual_tmp=deci%2
 >     dual=dual_tmp, dual <--- change dual here

Observations:
  this program does not reassign to deci; therefore it is an endless loop.
  while deci>0: can just be while deci:

Try this:
dual = ''
deci = input("Decimal? --> ")
while deci:
   deci,b = divmod(deci,2)
   dual=str(b)+dual
print dual

If you plan to use this a lot (where performance might be impacted) an 
alternative is:
# dictionary uses hex digits as keys values are corresponding binary strings
dict = {'0': '0000', '1': '0001', ... '9': '1001', 'A': '1010', ... 'F': 
'1111'} # fill in the ellipses!
hex = '%X' % deci # convert decimal to string of hex characters
dual = ''.join([dict[x] for x in hex]) # translate and combine

Bob Gailer
mailto:ramrom@earthling.net
303 442 2625

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