Strange behaviour with a for loop.

Mark Lawrence breamoreboy at yahoo.co.uk
Sat Jan 4 00:38:20 EST 2014


On 04/01/2014 04:03, Sean Murphy wrote:
> Hello all.
>
> This is a newly question. But I wish to understand why the below code is providing different results.
>
> import os, sys
>
>
> if len(sys.argv) > 2:
>    filenames = sys.argv[1:]
> else
>    print ("no parameters provided\n")
>    sys.edit()
>
> for filename in filenames:
>    print ("filename is: %s\n" %filename)
>
> The above code will return results like:
>
> filename is test.txt
>
> If I modify the above script slightly as shown below, I get a completely different result.
>
> if len(sys.argv) > 2:
>    filenames = sys.argv[1]
> else
>    print ("no parameters provided\n")
>    sys.exit()
>
> for filename in filenames:
>    print ("filename is:  %s\n" % filename)
>
> The result is the filename is spelled out a character at a time. The bit I am missing is something to do with splicing or referencing in Python.
>
> Why am I getting different results? In other languages I would have got the whole content of the element when using the index of the array (list).
>
>
> Sean
> filename is: t
> filename
>

As you've already had answers I'd like to point out that your test for 
len(sys.argv) is wrong, else is missing a colon and sys.edit() is very 
unlikely to work :)

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence




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