The Python 2.7 version differs from the 3.6 __python

Many Python beginners ask: Which version of Python should I learn? My answer to this question is usually "choose a python tutorial that works best for you, which version of Python is used in the tutorial, and you use that version." And so on, and then to study the differences between the different versions.

Many Python beginners ask: Which version of Python should I learn? My answer to this question is usually "choose a python tutorial that works best for you, which version of Python is used in the tutorial, and you use that version." And so on, and then to study the differences between the different versions.

But if you want to develop a new project in Python, how do you choose the Python version? I can responsibly say that most Python libraries support both the Python 2.7.x and 3.x versions, so whichever version you choose is OK. But in order to avoid some of the common pitfalls of some versions while using Python, or to migrate a Python project, it is still necessary to understand the main differences between the two common Python versions.

__future__ Module

Python 3.x introduces some of the keywords and features that are incompatible with Python 2, and in Python 2, you can import these new content through the built-in __future__ module. If you want code written in the Python 2 environment to run in Python 3.x, it is recommended that you use the __future__ module. For example, if you want to have the Python 3.x integer division behavior in Python 2, you can import the corresponding module through the following statement.

    
    
     
     From __future__ Import Division
    
    

The following table lists the other features that can be imported in __future__:

2.2.0a2

attributes	Optional version	enforce version	effect
nested_scopes	2.1.0b1	2.2	PEP 227:statically Nested scopes
generators	2.2.0a1	2.3	PEP 255:simple generators
Division	3.0	PEP 238:changing the division Operator
Absolute_impor T	2.5.0a1	3.0	PEP 328:imports:multi-line and absolute/relative
with_statement	2.5.0a1	2.6	PEP 343:the "with" Statement
print_function	2.6.0a2	3.0	PEP 3105:make print a function
unicode_literals	2.6.0a2	3.0	PEP 3112:bytes literals in Python 3000

(Source: https://docs.python.org/2/library/future.html)

Example:

    
    
     
     From platform import python_version
    
    

Print function

Although the print syntax is a small change in Python 3 and should already be well known, it is worth mentioning that the print statement in Python 2 is replaced by the print () function in Python 3, which means that the Python You must enclose the object you want to output in parentheses in 3.

It is also possible to use extra parentheses in Python 2. But conversely, when you want to call the print function without parentheses in the form of Python2 in Python 3, the syntaxerror is triggered.

Python 2

    
    
     
     print ' Python ', python_version ()
     
     print ' Hello, world! '
     
     Print (' Hello, world! ')
     
     Print "text",; print ' Print more text on the same line '
    
    

    
    
     
     Python 2.7.6
     
     Hello, world!
     
     Hello, world!.
     
     text Print more text on the same line
    
    

Python 3

    
    
     
     Print (' Python ', Python_version ())
     
     print (' Hello, world! '
     
     ) Print ("Some text,", end= "")
     
     print (' Print more text on the same line ')
    
    

    
    
     
     Python 3.4.1
     
     Hello, world!
     
     Some text, print more text on the same line
    
    

    
    
     
     print ' Hello, world! '