What's the difference between %r, %s and %d in python? [duplicate]

Answer 1

This is explained in the Python documentation. In short,

• %d will format a number for display.
• %s will insert the presentation string representation of the object (i.e. str(o))
• %r will insert the canonical string representation of the object (i.e. repr(o))

If you are formatting an integer, then these are equivalent. For most objects this is not the case.

Answer 2

Here is an example to supplement James Henstridge's answer:

class Cheese(float):
    def __str__(self):
        return 'Muenster'
    def __repr__(self):
        return 'Stilton'

chunk = Cheese(-123.4)

print(str(chunk))
# Muenster
print(repr(chunk))
# Stilton
print(int(chunk))
# -123
print('%s\t%r\t%d'%(chunk, chunk, chunk))
# Muenster  Stilton -123