[Tutor] checking if a variable is an integer?

[James Reynolds]

If prime numbers were finite (an ability to find *all *prime numbers) that
would cause havoc with the fundamental theorem of arithmetic ;)

On Tue, May 31, 2011 at 5:40 PM, Rachel-Mikel ArceJaeger <
arcejaeger at gmail.com> wrote:

> Isn't one of the unsolved millenium prize problems one that includes the
> ability to find all of the prime numbers? I'm not sure if your program is
> possible if the input number is large.
>
> But to check if a number x is an int, just do this:
>
> x == int(x)
>
>
> Rachel
>
>
> On Tue, May 31, 2011 at 2:38 PM, Hugo Arts <hugo.yoshi at gmail.com> wrote:
>
>> On Tue, May 31, 2011 at 11:30 PM, Joel Goldstick
>> <joel.goldstick at gmail.com> wrote:
>> >
>> >
>> >
>> http://stackoverflow.com/questions/1265665/python-check-if-a-string-represents-an-int-without-using-try-except
>> >
>> > def RepresentsInt(s):
>> >
>> >     try:
>> >         int(s)
>> >
>> >         return True
>> >     except ValueError:
>> >
>> >         return False
>> >
>> >>>> print RepresentsInt("+123")
>> >
>> > True
>> >>>> print RepresentsInt("10.0")
>> >
>> > False
>> >
>>
>> For strings, that works, but not for integers:
>>
>> >>> int(10.0)
>> 10
>>
>> And if you want to check if one number is divisible by another, you're
>> not going to call it on strings.
>>
>> A better way is to use the modulo operator, which gives the remainder
>> when dividing:
>>
>> >>> a = 6
>> >>> a % 3
>> 0
>> >>> a % 4
>> 2
>>
>> So, if the remainder is zero the left operand is divisible by the right
>> one.
>>
>> Hugo
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>
>
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