CODEWITHSUNDEEP
pythonpython-3.x
user7696063
user7696063

Reputation:

Number of digits using while true in Python

I'm writing a program on Python 3.6.1 that counts the number of digits of a given number by the user. I'm using the sentence "while True" and not functions or strings because I haven't learned to use them yet. Here is my code:

number=int(input("Write number: ")) 
cont=0
while True:
    number=number/10
    cont=cont+1
    if number==0:
        break 
print("The number of digits is: ", cont)

My problem is the the above code isn't working because when I put, let's say 123, the program gives me the value 326. I don't know what is wrong with my code, so how could I fix this?

Upvotes: 1

Views: 182

Answers (4)

Eric Miao
Eric Miao

Reputation: 11

you can try this way

number = int(input("Write Number:"))
b = len(str(number))
print(b)

or you can change '/' into '//' , it does work

update

b = len(str(abs(number)))

Upvotes: 0

Anton vBR
Anton vBR

Reputation: 18916

Is there a specific reason you don't convert the number to a string and use len(string)?

len(str(number))

Update (thanks to comment):

len(str(abs(number)))

Upvotes: 1

paxdiablo
paxdiablo

Reputation: 881623

Have a look at this:

Python 3.5.2 (default, Nov 17 2016, 17:05:23) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 123 / 10
12.3

Yes, / is floating point division in Python so it's not doing what you expect.

You can see what's actually happening if you insert print(number) immediately after the division-by-ten. It does division continuously until it gets a number so small it cannot tell the difference between it and zero:

12.3
1.23
0.123
0.0123
0.00123
0.000123
1.23e-05
1.23e-06
1.23e-07
1.2300000000000001e-08
1.23e-09
1.2300000000000001e-10
1.2300000000000002e-11
1.2300000000000002e-12
1.2300000000000003e-13
1.2300000000000003e-14
1.2300000000000003e-15
:
1.2299999999999997e-307
1.2299999999999997e-308
1.23e-309
1.23e-310
1.23e-311
1.23e-312
1.23e-313
1.23e-314
1.23e-315
1.23e-316
1.23e-317
1.23e-318
1.23003e-319
1.23e-320
1.23e-321
1.24e-322
1e-323
0.0

You can fix this by changing:

number=number/10

into either of:

number = int(number / 10)
number = number // 10

This will do integer division so will stop after the correct number of steps.

Upvotes: 1

happydave
happydave

Reputation: 7187

Python 3 does floating point division by default. You need to use integer division. number = number // 10.

Upvotes: 0

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