How can I flush the output of the print function? How can I flush the output of the print function? python python

How can I flush the output of the print function?


In Python 3, print can take an optional flush argument:

print("Hello, World!", flush=True)

In Python 2 you'll have to do

import syssys.stdout.flush()

after calling print. By default, print prints to sys.stdout (see the documentation for more about file objects).


Running python -h, I see a command line option:

-u : unbuffered binary stdout and stderr; also PYTHONUNBUFFERED=xsee man page for details on internal buffering relating to '-u'

Here is the relevant documentation.


Since Python 3.3, you can force the normal print() function to flush without the need to use sys.stdout.flush(); just set the "flush" keyword argument to true. From the documentation:

print(*objects, sep=' ', end='\n', file=sys.stdout, flush=False)

Print objects to the stream file, separated by sep and followed by end. sep, end and file, if present, must be given as keyword arguments.

All non-keyword arguments are converted to strings like str() does and written to the stream, separated by sep and followed by end. Both sep and end must be strings; they can also be None, which means to use the default values. If no objects are given, print() will just write end.

The file argument must be an object with a write(string) method; if it is not present or None, sys.stdout will be used. Whether output is buffered is usually determined by file, but if the flush keyword argument is true, the stream is forcibly flushed.


matomo