How do i print/return the number of lines in a file

Question

Possible Duplicate:
How to get line count cheaply in Python?

I'd like to print how many lines there is in a file.

What I have so far is this, but it prints the number of every line and I'm not sure how to get Python to only print the last one.

filename = input('Filename: ')

f= open(filename,'r') 

counter = 1 

line = f.readline() 
while(line): 
    clean_line = line.strip() 
    print(counter) 
    line = f.readline()
    counter += 1
f.close()

score 3 · Answer 1 · answered Nov 09 '12 at 11:18

3

I'd go for...

with open('yourfile') as fin:
    print sum(1 for line in fin)

This saves reading the file into memory to take its length.

answered Nov 09 '12 at 11:18

Jon Clements

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Best solution here. I was being overwhelmingly lazy. – Steve Mayne Nov 09 '12 at 14:02

score 1 · Answer 2 · answered Nov 09 '12 at 11:01

1

f = open(filename, 'r')
lines = f.readlines()
number_of_lines = len(lines)
f.close()

answered Nov 09 '12 at 11:01

Steve Mayne

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score 1 · Accepted Answer · answered Nov 09 '12 at 11:01

1

If you don't need to loop on each line, you could just use:

counter = len(f.readlines())

answered Nov 09 '12 at 11:01

Nicolas

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Thanks! Didn't know i could use the len function here! – Nikolai Stiksrud Nov 09 '12 at 11:06

How do i print/return the number of lines in a file

3 Answers3