Python 2 vs. Python 3: Which One Should You Learn?

Python 2 vs. Python 3: Which One Should You Learn?

Python has been around for 30 years, and the language has seen many changes through the decades. Over the years, there have been three main versions of the language: Python 1, Python 2, and Python 3.

While Python was still in its infancy in the first version, the second version (Python 2) saw massive popularity and was used for DevOps and backend development.

The most recent version saw support for data science and AI. So today, AI, Machine Learning, and Automation mostly run on Python 3.

Since Python 2 and Python 3 are the two main versions of this popular language, Python developers need to understand the differences between these two versions.

In a nutshell, the main differences lie in their application areas and syntax.  So continue reading if you want to learn more about them.


What is Python 2?

Python 2 (more officially, Python 2.0 or Python 2.x) was released in 2000 by the BeOpen Python Labs team with the goal of making programming easy.

Aside from simplified programming, Python 2 added multiple features such as list comprehension, Unicode support, and garbage collection.

Python also started supporting object-oriented programming from Python 2. So, developers naturally switched to Python 2 from Python 1.


What is Python 3?

Python 3 (more officially, Python 3.0 or Python 3.x) was released in 2008 and wasn't just a simple patch over Python 2. In fact, the upgrade to Python 3 saw many improvements and new features.

The first job of Python 3 was to remove redundancy while writing code. It was also created to eliminate most problems that programmers face (like error handling).

In addition to cosmetic improvements, Python 3 also made a far greater impact as it made Python the number one programming language in fields like AI, Automation, Data Science, Machine Learning, etc.


Python 2 vs. Python 3: Which One Should I Learn?

If you want to learn Python in 2022, you must remember that Python 2 is no longer in use. So, there is no point in learning Python 2, right?

Well, actually, no. There are still many legacy applications that work on Python 2, and there is a demand for people with Python 2 knowledge to maintain these systems.

But in general, Python 3 is a better Python version to learn. Most new programmers don't want to specialize, so Python 3 makes more sense.

Since Python 3 is more readable and functional, it is easier for beginners to learn. You might think that Python 3 doesn't have an extensive library. And yes, not many third-party libraries got a Python 3 upgrade in the initial stages.

But today, you will find many libraries that support this version.


Python 2 vs. Python 3: Syntax Differences

The main difference between Python 2 and Python 3 is their syntax. Python 3 has introduced many new ways to write code.

From print function to error handling and iterations, the syntax of the two versions is very different. Here's how they differ:

There are two ways to write the print function in Python 2:

  1. print 'Hello World'      
  2. print('Hello World')

Python 3 treats the print function as an actual function, so it doesn't support the version without the parentheses.

On the other hand, Python 2 treats the print function as a statement, so it doesn't require parentheses.


Division Operator

When we divide an integer with an integer, Python 2 outputs only the integer part. The decimal part is automatically discarded.

In Python 2,

  • print 17 / 5 will result in 3
  • print -17 / 5 will result in -4

Python 3 fixes this issue by calculating the actual result.

In Python 3,

  • print 17 / 5 will result in 3.4
  • print -17 / 5 will result in -3.4

Error Handling

Python 3 introduces a small change in error handling. The as keyword is required for error handling in Python 3.

Error Handling Syntax in Python 2 

Error Handling Syntax in Python 3 

try:

code_in_try_block


except Error1, err:

code_in_except block

try:

code_in_try_block


except Error1 as err:

code_in_except block



Iterations

In Python 3, we have the range() function for performing iterations. Python 2, on the other hand, made use of the xrange() function.

Python 2 

Python 3

for a in xrange(1, 10):

 

    print(a)

 


# Output: 1 2 3 4 5 6 7 8 9

for a in range(1,10):

 

    print(a)



# Output: 1 2 3 4 5 6 7 8 9



Unicode

Python 2 uses ASCII encoding in the case of strings, while Python 3 uses Unicode. In Python 2, ASCII and Unicode are different, but in Python 3, they are the same.

In Python 3, we can use the type function to see the encoding:

print(type('string'))

In the case of Python 2; we need to define a Unicode string with 'u' as shown below:

print(type(u'string with b'))


Comparison Table

To summarize, here is a comparison table showing the significant differences between Python 2 and Python 3:

Comparison Points 

Python  2

Python 3

Release Date

2000

2008

Syntax Difficulty 

Comparatively challenging to understand.

Comparatively easy to understand. 

Libraries

Most Python 2 libraries aren't compatible with Python 3.

Python 3 has tons of new libraries that programmers can use.

Backward Compatibility

Python 2 is not backward compatible with Python 1, but Python 2 code can be upgraded to Python 3. 

Python 3 code can't be used in Python 2 applications, so it isn't backward compatible. 

Iteration

We use the xrange() function to perform iterations in Python 2. 

Python 3 has the range() function to iterate variables. 

Error handling

We don't use the as keyword in the except block of error handling.

We have to use the as keyword in the except block of error handling. 

Division Operator

The division operator returns an integer value. 

The division operator returns a float value. 

Print Function

The print function is treated as a statement, so parentheses are unnecessary. 

The print function is treated as a function, so you need to use parentheses. 


Frequently Asked Questions

1. Is Python 3 faster than Python 2?

There are multiple sub-versions of both Python 2 and Python 3. Python 2.7 was the fastest Python version for a long time. But the recently released Python 3.7 beats it and is now the fastest Python version.

2. Can I use Python 2 and 3 together?

Yes, you can use Python 2 and 3 simultaneously on any Windows or Linux system. But remember to create different environments to use the versions separately. We cannot, however, write Python 3 code in Python 2 and expect it to run. On the other hand, most Python 2 code is supported in Python 3.

3. How do I convert Python 2 to Python 3 code?

The __future__ module is a built-in Python module that you can use if you want to inherit features that are only available in the newer versions of Python.

So, we can essentially convert Python 2 code to Python 3 using the __future__ module. For instance, let us change the division behavior of Python 2.

from __future__ import division

print 17/5

print -17/5
Python2 code with __future__ module

If you run the code above in Python 2, the result will be 3.4 and -3.4, even though Python 2 only prints the integer part of the answer by default.

4. Should I install both Python 3 and 2 together?

If you are working on both Python 2 and Python 3 projects on your computer, then you should definitely install both versions of Python.

You can also install them to research the differences between the two versions and see how they have evolved.