String Object Representation in Python

Question

What are the differences between the __str__() and str() methods in python?

check this https://docs.python.org/3/reference/datamodel.html. Look for __str__ — akshat, Apr 26 '18 at 04:22
In some sense, `str == operator.methodcaller('__str__')` defines the relationship between the two. — chepner, Apr 26 '18 at 04:42
@Jerrybibo Not quite. `str` is a *type*; `__str__` is an *instance* method. — chepner, Apr 26 '18 at 04:45
good point. @chepner I need to brush up on my terminologies. — Jerrybibo, Apr 26 '18 at 04:49

score 2 · Answer 1 · edited Apr 26 '18 at 04:34

__str__ (usually read dunder, for double under) is an instance method that is called whenever you run str(<object>) and returns the string representation of the object.

str(foo) acts as a function trying to convert foo into a string.

Note:
There is also a __repr__() method which is fairly similar to __str__(), the main difference being __repr__ should return an unambiguous string and __str__ is for a readable string. For a great response on the diffences between the two I'd suggest giving this answer a read.

score 0 · Answer 2 · edited Apr 26 '18 at 06:12

__str__() is a magic instance method that doee this: when you print a class instance variable with print(), it will give you a string that can be modified by changing the returned string in the __str__() method. There's probably a better explanation to it but I can show you with code:

class Thing:
    def __init__(self):
        pass
    def __str__(self):
       return "What do you want?"  #always use return

a = Thing()
print(a)

OUTPUT:

What do you want?

str() just converts a variable into a string type variable.

print(str(12.0))

OUTPUT:

'12.0'

You can confirm it is a string using the type() function.

print(type(str(12.)))

I don't know the exact output of that but it will peobably have 'str' in it.

String Object Representation in Python

2 Answers2