Question

I am writing a python program to copy a file line by line into a new file. The code I have is below in which I am using a loop to copy the file line by line.

However since the number of lines in the file may change, is there a way to copy a file line by line in python without using a loop which relies on numbers, and instead relies on the something like the EOF character to terminate the loop?

import os
import sys

i = 0
f = open("C:\\Users\\jgr208\\Desktop\\research_12\\sap\\beam_springs.$2k","r")
copy = open("C:\\Users\\jgr208\\Desktop\\research_12\\sap\\copy.$2k","wt")
#loop that copies file line by line and terminates loop when i reaches 10
while i < 10:
     line = f.readline()
     copy.write(str(line))
     i = i +1
f.close()
copy.close()

Answer 1

You can iterate over lines in a file object in Python by iterating over the file object itself:

for line in f:
    copy.write(line)

From the docs on file objects:

An alternative approach to reading lines is to loop over the file object. This is memory efficient, fast, and leads to simpler code:

>>> for line in f:
        print line,