Double-digit int to string and startswith()

Question

So, I have double-digit numbers below 100. Below 10 python doesn't handle them out-of-the-box. I have seen many different solutions, but I'm just fine with converting them to strings and then check whether the it starts with 0.

The below code is just a sample test of checking the above condition, but fails:

num = 01
if str(num).startswith('0'):
    print 'yepp'
else:
    print 'nope'

I keep getting "nope" for this very example. Why?

`01` is not a double-digit number. It's just `1`. (Actually, it's an octal literal, because of the leading `0`. Python won't even accept something like `08`, because `8` isn't an octal digit. On Python 3, octal literals need to start with `0o`, and Python 3 won't accept `01` at all.) — user2357112, Apr 05 '17 at 16:43
@user2357112 So if `08` is the input, how to convert it to 8 (int). Because I can't do any math stuff with a variable like `num = 08`. I get error for `print num*2`. — fishmong3r, Apr 05 '17 at 16:45
Could you state your number as a list of the digits then ints will work num = [0,1] if str(num[0])==0: print 'yepp' else: print 'nope' — CodeCupboard, Apr 05 '17 at 16:48
@fishmong3r: If you're reading numbers from user input, use `int(raw_input())` to read the input, interpret it as the base 10 representation of an integer, and produce the corresponding integer. This integer will not track leading zeros, because leading zeros are not a numeric property; if you want to print it with leading zeros, you can use Python's output formatting tools. — user2357112, Apr 05 '17 at 16:49
@user2357112 -- I didn't know that the "010"-meaning-8 had been dropped in Python3, but I heartily approve. The syntax probably caused me 1 bug for every 4 times I got any value from it, and that is a terrible ratio. — Michael Lorton, Apr 05 '17 at 16:50
OP,you can get what I think you want this way: [`"%02d" % num`](https://pyformat.info/). — Michael Lorton, Apr 05 '17 at 16:52

score 1 · Answer 1 · answered Apr 05 '17 at 16:43

1

num is not a string. It is an integer. The integer 1 does not start with '0' when converted to a string

answered Apr 05 '17 at 16:43

Devin

1,262
15
20

score 0 · Answer 2 · answered Apr 05 '17 at 16:43

The integer value 01 don't exist, it's equal to 1 in Python 2.x and will produce a SyntaxError in Python 3.x.

Code1:

>>> num = '01'
>>> if str(num).startswith('0'):
>>>     print('yepp')
>>> else:
>>>     print('nope')
yepp

Code2:

>>> num = 01
>>> if str(num).startswith('0'):
>>>     print('yepp')
>>> else:
>>>     print('nope')
File "<ipython-input-4-dafa449070e3>", line 1
  num = 01
         ^
SyntaxError: invalid token

Code3:

>>> num = 1
>>> if str(num).startswith('0'):
>>>     print('yepp')
>>> else:
>>>     print('nope')
nope

Double-digit int to string and startswith()

2 Answers2