Python way of printing: with 'format' or percent form? [duplicate]

In Python there seem to be two different ways of generating formatted output:

user = "Alex"
number = 38746
print("%s asked %d questions on stackoverflow.com" % (user, number))
print("{0} asked {1} questions on stackoverflow.com".format(user, number))

Is there one way to be preferred over the other? Are they equivalent, what is the difference? What form should be used, especially for Python3?

Solution 1:

Use the format method, especially if you're concerned about Python 3 and the future. From the documentation:

The formatting operations described here are modelled on C's printf() syntax. They only support formatting of certain builtin types. The use of a binary operator means that care may be needed in order to format tuples and dictionaries correctly. As the new :ref:string-formatting syntax is more flexible and handles tuples and dictionaries naturally, it is recommended for new code. However, there are no current plans to deprecate printf-style formatting.

Solution 2:

.format was introduced in Python2.6

If you need backward compatibility with earlier Python, you should use %

For Python3 and newer you should use .format for sure

.format is more powerful than %. Porting % to .format is easy but the other way round can be non trivial

Solution 3:

The docs say that the format method is preferred for new code. There are currently no plans to remove % formatting, though.