what's the meaning of %r in python

In Python, there are two builtin functions for turning an object into a string: str vs. repr. str is supposed to be a friendly, human readable string. repr is supposed to include detailed information about an object’s contents (sometimes, they’ll return the same thing, such as for integers). By convention, if there’s a Python expression that will eval to another object that’s ==, repr will return such an expression e.g.

print repr(‘hi’)
‘hi’ # notice the quotes here as opposed to…

print str(‘hi’)
hi
If returning an expression doesn’t make sense for an object, repr should return a string that’s surrounded by < and > symbols e.g. .
To answer your original question:
%s <-> str
%r <-> repr
In addition:
You can control the way an instance of your own classes convert to strings by implementing str and repr methods.
class Foo:
def init(self, foo):
self.foo = foo
def eq(self, other):
“”“Implements ==.”""
return self.foo == other.foo
def repr(self):

# if you eval the return value of this function,
# you'll get another Foo instance that's == to self
return "Foo(%r)" % self.foo