Why the following python code always returning false?

Question

Input file Test.ini:

;INTEGRITY_PERIOD=300  
INTEGRITY_PERIOD=100

Code:

key = None
value = None

with open('hmi.ini', 'r') as inifile:
    for line in inifile:
        if line.startswith(';INTEGRITY_PERIOD='):
            continue;
        if line.startswith('INTEGRITY_PERIOD='):
            key, value = line.split("=")
            break

if value and value.isdigit():
    print(value)
else:
    print(300)

The above code is always returning 300. Looks like isdigit() is not working or is there anything wrong in my code ?

Martijn Pieters · Accepted Answer · 2017-04-25 09:05:30Z

5

Your lines end in a line separator, which you did not remove. Strip the line to remove whitespace from the start and end:

key, value = line.strip().split("=")

A line separator (\n) is not a digit:

>>> '100\n'.isdigit()
False
>>> '100'.isdigit()
True

Rather than build your own parser, consider using the configparser module from the standard library. It fully supports the INI format (including using ; as a comment).

answered Apr 25, 2017 at 9:05

Martijn Pieters

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3 Comments

lennyklb Over a year ago

When selecting the text in the provided code sample, it seems as though there are some spaces rather than a newline (though I'm not sure if this is just a formatting issue or not). When iterating over the lines, aren't newlines omitted automatically? Anyway, .strip() naturally handles any whitespace, be they spaces or newlines

Martijn Pieters Over a year ago

@LennartKloppenburg: no, newlines are not omitted.

Deepak Nayak Over a year ago

configparser module is really very useful. Thanks for letting me know about this library.

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