About Identifiers in Python| #02 |

What is Identifier? 

⇒ A Python identifier is a name of an Object.

⇒ An identifier is used to identify an object.

⇒ Objects can be Variables, Functions, Class, Module, and any other Object.

Python has some rules to give names as Identifiers.

⇒ Identifiers can contain only Alphabetic a to z, A to Z, Digits(0 to 9), and Underscore( _ )

For Example 

(Here we denoted, Red for Invalid and Green For Valid Identifier)

⇨ car , Car , CAR , Bus , DEv , abc23 , a1b2 , lsky , _dev_shah , LSky_education123 etc. 

⇒ Identifiers Should not start from the number(digits).

For Example 

⇨ 1dev , 5434 , 434shah , 0car , 0_abc123 , etc.

⇒ Identifiers can not contain any white-space.

For Example 

⇨ dev shah , LSky education , ab c , ab12cd efgh , xyz_2  abc , etc.

⇒ There are not allowed to use Symbolic Characters such as @, $, %, etc.

For Example 

⇨ dev@shah , LSky$education , ab%c , @b12cdefgh , xyz_2!abc , abcd()xyz , abc~efg , etc.

(NOTE: if we use '#' symbol in side identifier's name like: abcd#xyz . It will generate NameError because In Python '#' symbol is used to write comments.)

⇒ There are not allowed to Operators Symbolic Characters such as ^, &, *, / , - , +,  etc.

For Example 

⇨ xyz%abc , xyz^abc , xyz&abc , xyz*abc , xyz-abc , xyz+abc , xyz\abc , xyz/abc , xyz:abc , etc.

⇒ Python is case sensitive programming language So, In Python identifiers ' car ' and ' Car ' are different identifiers.

For Example 

    

    abc="this is first variable"

    Abc="this is second variable"

    ABC="this is Third variable"

    

    print(abc)

    print(Abc)

    print(ABC)

Output:

this is first variable this is second variable this is Third variable

⇒ There is no length limit for Python identifiers. But not recommended to use too lengthy
identifiers.

⇒ Class names start with an uppercase letter. All other identifiers start with a lowercase letter.

⇒  If Identifier is start with Single Underscore (_) then it indicates it is private.

For Example: _abc

⇒  If identifier starts with (Two Underscore Symbols) indicating that strongly private identifier.

For Example: __abc

⇒ If the identifier starts and also ends with two underscore symbols then the identifier is language defined special name, which is also known as magic methods.

For Example: __abc__