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### how do i convert a number in base b to a number in base 10 using python

Apr 27th, 2004 00:08

```Of course it will depend on how the number in base b is stored, but the
most common situation is that you have a string in base b, using the
digits from 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ. Actually, this only
works for base 2 through base 36... for larger bases there is no
standard convention for digits.
So the constructor for int is designed to handle any base from 2
through 36:
>>> int('FF', 16) # hexadecimal (base 16)
255
>>> int('777', 8) # base 8
511
>>> int('10000011', 2) # binary
131
>>> int('1234', 10) # decimal
1234
>>> int('1234') # defaults to decimal if not specified
1234
--------------------------------------------------------------
And if you want the opposite, something like converting from decimal to
binary you can code a function like:
def tobase(b,n,result=''):
if n == 0:
if result:
return result
else:
return '0'
else:
or, more safe and complete:
def tobase(base,number):
global tb
def tb(b,n,result=''):
if n == 0: return result
else: return tb(b,n/b,str(n%b)+result)
if type(base) != type(1):
raise TypeError, 'invalid base for tobase()'
if base <= 0:
raise ValueError, 'invalid base for tobase(): %s' % base
if type(number) != type(1) and type(number) != type(1L):
raise TypeError, 'tobase() of non-integer'
if number == 0:
return '0'
if number > 0:
return tb(base, number)
if number < 0:
return '-' + tb(base, -1*number)
bin = lambda n: tobase(2,n)
Abdel Wahab Salah
http://www.free-web-hosting.org.ru```