Python - How to get the number of lines in a text file [duplicate]

Question

I would like to know if it s possible to know how many lines contains my file text without using a command as :

with open('test.txt') as f:
    text = f.readlines()
    size = len(text)

My file is very huge so it s difficult to use this kind of approach...

Answer 1

As a Pythonic approach you can count the number of lines using a generator expression within sum function as following:

with open('test.txt') as f:
   count = sum(1 for _ in f)

Note that here the fileobject f is an iterator object that represents an iterator of file's lines.