Python 2 Vs Python 3

Initial Version and Released Year

Python 2.0 – Released in the year 2000

Python 3.0 – Released in the year 2008

Latest Version and Released Year

Python 2.7 – Released in the year 2010

Python 3.6 – Released in the year 2016

Version in Development

None

Python 3.7 under development

Stability

Python 2 is steadier and more translucent version

Python 3 is to manage the design defects in the earlier versions

Complexities

Python 2 syntax is complex

Python 3 syntax is simple and easy to understand

Working of Print Statement

Python 2 Print syntax is treated as a statement.

Example: print(“hello”)

Python 3 Print syntax is plainly treated as a function.

Example: print “hello”

Integer Division

In Python 2, dividing two (2) integers constantly return a nearest whole number

In Python 3, dividing two (2) integers result in an integer value

Example of Integer Division

3.0/2.0 = 1

3.0/2.0= 1.5

Python Libraries

A large number of old Libraries are existing for Python 2 in many OS which is not forward-compatible

Libraries are being developed and they are made strict to use with Python 3

Unicode Support

Strings are stored as ASCII by default in Python 2. Add a prefix with “u” to make Unicode string

Text strings are Unicode by default in Python 3

String and Bytes

String and Bytes are treated as same in Python 2

String and Bytes are not treated as same in Python 3

Handy Function

Two (2) handy functions to create a range of integers in Python 2: range and xrange functions

One (1) handy function to create a range of integers in Python 3: range function

Example of Handling Exception

except IOError, err:

except IOError as err:

Leak of for-loop variables

For-loop variable leaks into the global namespace

For-loop variable does not leak into the global namespace

.next() method

Both .next() method and next() functions are available in Python 2. This is to draw the following element of an iterator

next() function is only available in Python 3 to draw the following element of an iterator

input() method

There are two (2) methods in Python 2 to take input: input() and raw_input()

Python 3 has only one input taking method which is input(). raw_input() is not available in Python 3. In case to use raw_input() like Python 2, make use of eval () method

Not equal operator

For not equal operator in Python 2, use greater than and lesser than signs

For not equal operator in Python 3, use general signs like exclamation marks and equal to

Rules of Ordering Comparison

Rules of ordering comparison in Python are extremely complex

Rules of ordering comparisons in Python 3 have been made simpler