file.readlines leaving blank lines [duplicate]

Question

I have read that file.readlines reads the whole file line by line and stores it in a list. If I have a file like so -

Sentence 1
Sentence 2
Sentence 3

and I use readlines to print each sentence like so -

file = open("test.txt") 
for i in file.readlines():
    print i

The output is

Sentence 1

Sentence 2

Sentence 3

My question is why do I get the extra line between each sentence and how can I get rid of it?

UPDATE

I found that using i.strip also removes the extra lines. Why does this happen? As far as I know, split removes the white spaces at the end and beginning of a string.

Answer 1

file.readlines() return list of strings. Each string contain trailing newlines. print statement prints the passed parameter with newlnie.; That's why you got extra lines.

To remove extra newline, use str.rstrip:

print i.rstrip('\n')

or use sys.stdout.write

sys.stdout.write(i)

BTW, don't use file.readlines unless you need all lines at once. Just iterate the file.

with open("test.txt") as f:
    for i in f:
        print i.rstrip('\n')
        ...

UPDATE

In Python 3, to prevent print prints trailing newline, you can use print(i, end='').

In Python 2, you can use same feature if you do : from __future__ import print_function

Answer to UPDATE

Tabs, Newlines are also considers as whitespaces.

>> ' \r\n\t\v'.isspace()
True