On 4/10/2014 9:54 AM, length power wrote:
 >>> x=['','x1','x2','x3','   ']
 >>> x
['', 'x1', 'x2', 'x3', '   ']
 >>> [print("ok") for it in x if it.strip() !=""]

Don't use comprehensions for side effects. To get what you want, just write normal code.

for it in x:
  if it.strip() != '':
    print('ok')

ok
ok
ok
[None, None, None]

i understand there are three 'ok' in the output,but why i have the
output of [None, None, None]

Reread the ref manual section on comprehensions.

--
Terry Jan Reedy

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