Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
144 views
in Technique[技术] by (71.8m points)

Python 2.7: Print to File

Why does trying to print directly to a file instead of sys.stdout produce the following syntax error:

Python 2.7.2+ (default, Oct  4 2011, 20:06:09)
[GCC 4.6.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> f1=open('./testfile', 'w+')
>>> print('This is a test', file=f1)
  File "<stdin>", line 1
    print('This is a test', file=f1)
                            ^
SyntaxError: invalid syntax

From help(__builtins__) I have the following info:

print(...)
    print(value, ..., sep=' ', end='
', file=sys.stdout)

    Prints the values to a stream, or to sys.stdout by default.
    Optional keyword arguments:
    file: a file-like object (stream); defaults to the current sys.stdout.
    sep:  string inserted between values, default a space.
    end:  string appended after the last value, default a newline.

So what would be the right syntax to change the standard stream print writes to?

I know that there are different maybe better ways to write to file but I really don't get why this should be a syntax error...

A nice explanation would be appreciated!

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Answer

0 votes
by (71.8m points)

If you want to use the print function in Python 2, you have to import from __future__:

from __future__ import print_function

But you can have the same effect without using the function, too:

print >>f1, 'This is a test'

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...