hey guys, i want to perform the following operation:
b = 'random'
c = 'stuff'
a = '%s' + '%s' %(b, c)
but i get the following error:
TypeError: not all arguments converted during string formatting
does any one of you know to do so ?
3 Answers
'%s%s' % (b, c)
or
b + c
or the newstyle format way
'{0}{1}'.format(a, b)
Comments
Depending on what you want :
>>> b = 'random'
>>> c = 'stuff'
>>> a = '%s' %b + '%s' % c
>>> a
'randomstuff'
>>>
>>> b + c
'randomstuff'
>>>
>>> z = '%s + %s' % (b, c)
>>> z
'random + stuff'
>>>
3 Comments
Paulo
wow, thanks guys, i didn't know about the precedence part , i ended up doing it like : a = '%b%c' %(b,c)
Nick T
@paulo: If all you're doing is concatenating strings, please just use
+. Simple and clear.
pyfunc
@Nick T: @paulo: The reason, I simply showed the various examples was that the intent of the code in question was not clear. The advices in the various replies and comments holds. If you are concatenating, do it directly, for formatting use "%" approach and even better the 'format' as suggested by sdolan.
Due to operator precedence, your program is first trying to substitue b and c into second '%s'. Therefore splitting such strings with + is meaningless, it's better to do
a = '%s %s' % (b,c)
%has a higher precedence than+so the compiler reads it as'%s' + ( '%s' % (b, c) )which fails as there is only one pattern for two values.a = ('%s' + '%s') % (b, c)also work? Because this seems to be just an operator precedence problem...('%s' + '%s')will combine into('%s%s'). Declaring('%s%s')is the same as'%s%s', so you end up with the same thing as'%s%s' % (b, c).