[Tutor] IPcount = 0 when used with subprocess.call (use something to convert to integer?)

Prasad, Ramit ramit.prasad at jpmorgan.com
Tue May 8 18:17:25 CEST 2012

> def count_lines(filename):
>     with open(f, 'r') as in_stream:
>         return len(in_stream.readlines())
> The count_lines function takes a filename and returns the number of
> lines in that file.  This way you avoid the problems with shell
> metacharacters when using shell=True, mentioned in the subprocess
> documentation:
> http://docs.python.org/py3k/library/subprocess.html#frequently-used-
> arguments

Or for large files where you do not want to read the entire file
to memory at the same time (assuming Python 2.x; not sure if 3.x 
stops the variable leakage I use here)

def count_lines(filename):
    with open(f, 'r') as in_stream:
         idx = 0
         for idx, line in enumerate(in_stream, 1):
         return idx

Ramit Prasad | JPMorgan Chase Investment Bank | Currencies Technology
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