Difference between Python 2 and Python 3

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Python 2.x and Python 3.x are two of the most used Python versions in real-world application development. They both come with a lot of features and library support. Although, official support for Python 2.x was discontinued in 2020. This article explores the major difference between Python 2 and 3.

What is Python 2?

Python 2 is an older version of the Python programming language, released in the year 2000. It introduced many features that helped shape the language, such as Unicode support, garbage collection, and list comprehensions. Python 2 was known for its simplicity and ease of learning, making it popular in educational and development settings. However, its official support ended in 2020, which means it no longer receives updates or security fixes.

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What is Python 3?

Python 3 is the currently and actively supported version of Python, first released in 2008. It was designed to rectify fundamental design flaws in Python 2 and improve the language's capabilities. Key improvements include better Unicode support, a more consistent syntax, and enhanced library functions. Python 3 encourages more efficient and sustainable code practices. It is the recommended version for all Python development due to its ongoing support and advanced features.

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Python 2 vs. Python 3: What’s the Difference?

Here's the table that illustrates difference between Python 2 and 3.

Comparison ParameterPython 2Python 3
Release YearDebuted in 2000.Debuted in 2008.
print FunctionalityThe print is a statement.The print is a function.
String StorageASCII is the default string type.UNICODE is the default string type.
Integer DivisionResults in an integer quotient.Results in a floating-point quotient.
Exception SyntaxExceptions use 'notations'.Exceptions use 'parentheses'.
Global Variable LeakGlobal variables can leak inside loops.Global variables are stable inside loops.
Iteration MethodUses the xrange() for iterations.Introduces the range() function for iteration.
Syntax SimplicityHas a more complex syntax.Has a simpler and more intuitive syntax.
Library CompatibilityLibraries are less forward-compatible.Libraries are designed to be strictly compatible with Python 3.
Current UsageNo longer in use since 2020.More popular and actively used today.
Backward Compatibilitycode can be ported to Python 3 with effort.Not backward compatible with Python 2.
Primary UseWas mainly used for DevOps engineering. No longer in use post-2020.Widely used in diverse fields such as Software Engineering, Data Science, etc.

Python 2 vs. Python 3 Example Code

This below code explains the major difference between python 2 and 3: Python 2

Output:

Python 3

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This example demonstrates the difference between Python 2 and Python 3, including the print statement/function, integer division, range/xrange functions, input function, handling of Unicode strings, and error handling.

Python 2 or 3: Which Python Version is Best?

One of the most common questions that arises is, "Which Python version is better: Python 2 or Python 3?" After examining the differences between the two versions, the answer becomes clear. Python 3 emerges as the victorious version.

First and foremost, Python 2 has been phased out since 2020, making Python 3 the standard choice. This transition was driven by the recognition that Python 3 offers a safer and more sustainable option, particularly for aspiring programmers who are still exploring their coding journey. Python 3 boasts improved readability, ease of comprehension, and widespread adoption compared to Python 2.

This shift underscores Python 3 as the preferred choice for developers, offering modern features, enhanced capabilities, and long-term viability for projects of all sizes.

Reasons to Learn Python 2

Reasons for using Python 2 are:

  • Legacy Code Maintenance: Understanding Python 2 is essential for maintaining and updating legacy systems that still operate on this version.
  • Migration Projects: Skills in Python 2 are needed to transition code to Python 3, a common requirement for many organizations.
  • Educational Value: Learning Python 2 can provide insights into the evolution of programming languages and the rationale behind design changes.

Reasons to Learn Python 3

Reasons for using Python 3 are:

  • Enhanced Features: It offers improved functionality, such as advanced string handling and better memory management.
  • Wide Library Support: A vast array of modern libraries are available and are regularly updated.
  • Compatibility: New tools and frameworks are designed to work with Python 3, ensuring compatibility with the latest technologies.

Why are there different Python versions?

  1. The new print() function

In Python 2, the print is a statement. However, in Python 3, the print statement has been replaced by the print() function.

Python 2:

Python 3:

  1. Integer division

In Python 2, integer division behaves differently from Python 3. When dividing two integers in Python 2, the result is an integer, and any remainder is discarded.

Python 2:

Here, dividing 10 by 3 results in 3, as the decimal part is truncated.

Python 3:

Dividing 10 by 3 results in 3.3333333333333335, retaining the decimal part. Python 3 performs actual division by default, providing a more accurate result.

3. Unicode support

Python 2 and Python 3 handle Unicode strings differently. In Python 2, Unicode strings are prefixed with a "u" to distinguish them from ASCII strings. In Python 3, strings are stored as Unicode by default.

Python 2:

Python 3:

4. Range function

Python 2 and Python 3 have different implementations of the range function. In Python 2, the xrange() function generates a sequence of numbers on demand, while in Python 3, the range() function returns a sequence of numbers immediately.

Python 2:

Python 3:

Conclusion

  • The transitional journey from Python 2 to Python 3 signifies a significant evolution in the Python programming language.
  • Python 3 offering numerous improvements and enhancements.
  • Python 3 boasts better Unicode support, consistent syntax, and enhanced library functions compared to Python 2.
  • Official support for Python 2 ended in 2020, making Python 3 the standard choice for new projects and development efforts.
  • Python 3 is recommended for its ongoing support, modern features, and compatibility with the latest technologies.

FAQs

Q. What is the difference between print in Python 2 and 3?

A. In Python 2, print functions as a statement, so parentheses are optional around the text to be printed, but this can cause ambiguity as it diverges from the standard use of functions, which necessitates enclosing arguments in parentheses.

Misleading results may emerge when parentheses are used around a series of items to be printed, separated by commas. Conversely, in Python 3, print is a function, thus requiring the items to be enclosed within parentheses following conventional syntax; failing to do so results in a syntax error.

Q. Which is faster: Python 2 or 3?

A. Python 3 has made significant improvements in speed and efficiency over Python 2, especially in the latest versions. Early on, Python 3 was criticized for being slower, but with optimizations like the introduction of the asyncio library and more efficient data structures, it has closed the performance gap. While specific tasks might run faster in Python 2, Python 3's overall performance enhancements and future optimization potential generally make it the faster and more robust choice for modern applications.

Q. Can I install both Python 2 and 3?

A. Yes, you can install both Python 2 and Python 3 on the same system. They are treated as separate programs and can coexist without interference. It's common to use a version management system like pyenv or to rely on virtual environments to switch between versions for different projects. However, you should be cautious about the default python command on your system, as it may point to either Python 2 or 3, depending on the installation and path settings.

Q. Is Python 3 the same as Python?

A. Yes, when people refer to "Python" in the context of current programming, they are typically referring to Python 3. Python 3 is the latest and actively maintained version of the Python programming language. Python 2, the previous version, reached its end of life in 2020 and is no longer updated. So, in modern usage, "Python" implies Python 3.

Q. Is Python 3 a CPython?

A. Yes, Python 3 can refer to CPython when discussing implementations. CPython is the original and most widely used implementation of the Python programming language, which is written in C. When people talk about Python 3, they often mean CPython 3, which is the standard implementation of the Python 3 language specification. There are other implementations like PyPy, Jython, and IronPython, but CPython is the reference implementation that most people use and refer to when they talk about Python 3.

Q. Can I use Python 2 and 3 together?

A. Using Python 2 and Python 3 together in the same project is generally not recommended due to compatibility issues. They have different syntaxes and library behaviours. However, you can work on separate projects that use Python 2 and Python 3 on the same machine, using tools like virtual environments or version managers to keep their dependencies and settings isolated. For code that needs to be compatible with both versions, you can use compatibility libraries like six, but managing such code can be complex and is usually only done if necessary.