从文件读取时为什么打印新行？

Question

When I run this code I see new line.
I resolved it by adding rCourse.split() instead of rCourse .
But I am still curious about why new line is printed?

test.py

f = open('/home/test.txt', 'r')
print "oldCourses are:"
for rCourse in  f:
   print rCourse

test.txt

course1
course2
course3
adsfgsdg
sdgsfdg
sfbvfsbv
fbf

oldOutput

course1

course2

course3

adsfgsdg

sdgsfdg

sfbvfsbv

fbf

fsbf

Answer 1

Because your lines end with the '\\n' character and print adds another '\\n'.

There are multiple ways to fix this. I like to use the Python 3 print function.

from __future__ import print_function

f = open('test.txt', 'r')
print("oldCourses are:")
for rCourse in  f:
   print(rCourse, end='')

Answer 2

Suppose you have this text file:

$ cat test.txt
Line 1
Line 2
Line 3
Line 4

If you open that and read and print line-by-line you get two \\n for each line; one that is in each line of the file and one put there by default by print :

>>> with open("test.txt") as f:
...    for line in f:
...       print line
... 
Line 1

Line 2

Line 3

Line 4

There many ways to manage that.

You can use .rstrip() to remove the \\n :

>>> with open("test.txt") as f:
...    for line in f:
...       print line.rstrip()
... 
Line 1
Line 2
Line 3
Line 4

You can use a , to suppress the automatic \\n :

>>> with open("test.txt") as f:
...    for line in f:
...       print line,
... 
Line 1
Line 2
Line 3
Line 4

In Python 3.x use the print function which can also be imported in Python 2.

Cheers!