"==" and "is" in Python - Printable Version

"==" and "is" in Python - Printable Version

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+---- Thread: "==" and "is" in Python (/showthread.php?tid=4713)

"==" and "is" in Python - Canoris - 02-07-2010

Yesterday I was working with some code, and I used the "is" instead of the "==" as following:

Code:
import os

h = '[]>: '

while 1 > 0:

    p = raw_input(h)

    if (p is 'h?' or p is '--help'):

        h = '[h?]>: '

        print('\th?, --help\t\t\t-shows this list of commands\n\tpy?, --python\t\t\t-start interactive python in CLI\n\tpydle?, --python-idle\t\t\t')

    if (p is 'py?' or p is '--python'):

        h = '[py?]>: '

        os.system('python2.6')

    if (p is '--exit' or p is 'x?'):

        os.system('clear') and os.system('cls')

        print('Goodbye')

        break

    if (p is 'cs?' or p is '--clear'):

        h = '[cs?]>: '

        os.system('clear') and os.system('cls')

    if (p is 'lst?' or p == '--list'):

        h = '[lst?]>: '

        print(os.listdir('.'))

And it would just pass all of the if statements.... but when I replaced the "is" with the "==" it worked correctly. Any ideas? I thought they were the same operators?

RE: "==" and "is" in Python - uber1337 - 02-07-2010

It seems to be the characters used in the commands(-- and ?). I guess "is" doesn't evaluate those. Here is an example using and interactive session with python.

Code:
>>> p = 'h'

>>> if p is 'h':

    print 'hi'

hi

>>> p = 'h?'

>>> if p is 'h?':

    print 'hi'

>>> p = '--h'

>>> if p is '--h':

    print 'hi'

>>> if p == '--h':

    print 'hi'

hi

>>>

I guess it's just safer to use "==".