How to count lines in a text file ?

Bengt Richter bokr at
Wed Sep 22 19:59:30 CEST 2004

On Mon, 20 Sep 2004 15:29:18 +0200, aleaxit at (Alex Martelli) wrote:

>Ling Lee <janimal at> wrote:
>> Oh I just did it.
>> Just used the line:
>> print "%d lines in your choosen file" % len(open("test.txt").readlines())
>> Thanks though :)
>You're welcome;-).  However, this approach reads all of the file into
>memory at once.  If you must be able to deal with humungoug files, too
>big to fit in memory at once, try something like:
>numlines = 0
>for line in open('text.txt'): numlines += 1

I don't have 2.4, but how would that compare with a generator expression like (untested)

    sum(1 for line in open('text.txt'))

or, if you _are_ willing to read in the whole file,


Bengt Richter

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