How to change any data type into a string in Python?

Any built-in data type converted into its string representation by str() function

>>> str(10)
'10'
>>> str(11.11)
'11.11'
>>> str(3+4j)
'(3+4j)'
>>> str([1,2,3])
'[1, 2, 3]'
>>> str((1,2,3))
'(1, 2, 3)'
>>> str({1:11, 2:22, 3:33})
'{1: 11, 2: 22, 3: 33}'

For a user defined class to be converted to string representation, __str__() function needs to be defined in it.

>>> class rectangle:
def __init__(self):
self.l=10
self.b=10
def __str__(self):
return 'length={} breadth={}'.format(self.l, self.b)

>>> r1=rect()
>>> str(r1)
'length = 10 breadth = 10'