Python Tutorial

Introduction Python Features Python Applications System requirements for Python Python Installation Python Examples Python Basics Python Indentation Python Variables Python Data Types Python IDE Python Keywords Python Operators Python Comments Python Pass Statement

Python Conditional Statements

Python if Statement Python elif Statement Python If-else statement Python Switch Case

Python Loops

Python for loop Python while loop Python Break Statement Python Continue Statement Python Goto Statement

Python Arrays

Python Array Python Matrix

Python Strings

Python Strings Python Regex

Python Built-in Data Structure

Python Lists Python Tuples Python Lists vs Tuples Python Dictionary Python Sets

Python Functions

Python Function Python min() function Python max() function Python User-define Functions Python Built-in Functions Python Recursion Anonymous/Lambda Function in Python python apply() Function Python lambda() Function

Python File Handling

Python File Handling Python Read CSV Python Write CSV Python Read Excel Python Write Excel Python Read Text File Python Write Text File Read JSON File in Python

Python Exception Handling

Python Exception Handling Python Errors and exceptions Python Assert

Python OOPs Concept

OOPs Concepts in Python Classes & Objects in Python Inheritance in Python Polymorphism in Python Python Encapsulation Python Constructor Python Super function Python Static Method Static Variables in Python Abstraction in Python

Python Iterators

Iterators in Python Yield Statement In Python

Python Generators

Python Generator

Python Decorators

Python Decorator

Python Functions and Methods

Python Built-in Functions Python String Methods Python List Methods Python Dictionary Methods Python Tuple Methods Python Set Methods

Python Modules

Python Modules Python Datetime Module Python Math Module Python Import Module Python Time Module Python Random Module Python Calendar Module CSV Module in Python Python Subprocess Module Python Subprocess

Python MySQL

Python MySQL Python MySQL Client Update Operation Delete Operation Database Connection Creating new Database using Python MySQL Creating Tables Performing Transactions

Python MongoDB

Python MongoDB

Python SQLite

Python SQLite

Python Data Structure Implementation

Python Stack Python Queue Python Linked List Python Hash Table Python Graph

Python Advance Topics

Speech Recognition in Python Face Recognition in Python Python Linear regression Python Rest API Python Command Line Arguments Python JSON Python Virtual Environment Type Casting in Python Python Collections Python Commands Python Data Visualization Python Debugger Python DefaultDict Python Enumerate

Python 3

Anaconda in Python 3 Anaconda python 3 installation for windows 10 List Comprehension in Python3

Misc

Python PPTX Python Pickle Python Seaborn Python Coroutine Python EOL Python Infinity Python math.cos and math.acos function Python Project Ideas Based On Django Reverse a String in Python Reverse a Number in Python Python Word Tokenizer Python Trigonometric Functions Python try catch exception GUI Calculator in Python Implementing geometric shapes into the game in python Installing Packages in Python Python Try Except Python Sending Email Socket Programming in Python Python CGI Programming Python Data Structures Python abstract class Python Compiler Python K-Means Clustering NSE Tools In Python Operator Module In Python Palindrome In Python Permutations in Python Pillow Python introduction and setup Python Functionalities of Pillow Module Python Argmin Python whois Python JSON Schema Python lock Return Statement In Python Reverse a sentence In Python tell() function in Python Why learn Python? Write Dictionary to CSV in Python Write a String in Python Binary Search Visualization using Pygame in Python Latest Project Ideas using Python 2022 Closest Pair of Points in Python ComboBox in Python Python vs R Best resources to learn Numpy and Pandas in python Check Letter in a String Python Python Console Python Control Statements Convert Float to Int in Python using Pandas Difference between python list and tuple Importing Numpy in Pycharm Python Key Error Python NewLine Python tokens and character set Python Strong Number any() Keyword in python Best Database in Python Check whether dir is empty or not in python Comments in the Python Programming Language Convert int to Float in Python using Pandas Decision Tree Classification in Python End Parameter in python __GETITEM__ and __SETITEM__ in Python Python Namespace Python GUI Programming List Assignment Index out of Range in Python List Iteration in Python List Index out of Range Python for Loop List Subtract in Python Python Empty Tuple Python Escape Characters Sentence to python vector Slicing of a String in Python Executing Shell Commands in Python Genetic Algorithm in python Get index of element in array in python Looping through Data Frame in Python Syntax of Map function in Python After Python What Should I Learn Python AIOHTTP Alexa Python Artificial intelligence mini projects ideas in python Artificial intelligence mini projects with source code in Python Find whether the given stringnumber is palindrome or not First Unique Character in a String Python Python Network Programming Python Interface Python Multithreading Python Interpreter Data Distribution in python Flutter with tensor flow in python Front end in python Iterate a Dictionary in Python Iterate a Dictionary in Python – Part 2 Allocate a minimum number of pages in python Assertion Errors and Attribute Errors in Python Checking whether a String Contains a Set of Characters in python Python Control Flow Statements *Args and **Kwargs in Python Bar Plot in Python Conditional Expressions in Python Function annotations() in Python How to Write a Configuration file in Python Image to Text in python import() Function in Python Import py file in Python Multiple Linear Regression using Python Nested Tuple in Python Python String Negative Indexing Reading a File Line by Line in Python Python Comment Block Base Case in Recursive function python ER diagram of the Bank Management System in python Image to NumPy Arrays in Python NOT IN operator in Python One Liner If-Else Statements in Python Sklearn in Python Python Ternary Operators Self in Python Python vs Java Python Modulo Python Packages Python Syntax Python Uses Python Bitwise Operators Python Identifiers Python Matrix Multiplication Python AND Operator Python Logical Operators Python Multiprocessing Python Unit Testing __init__ in Python Advantages of Python Is Python Case-sensitive when Dealing with Identifiers Python Boolean Python Call Function Python History Python Image Processing Python main() function Python Permutations and Combinations Difference between Input() and raw_input() functions in Python Conditional Statements in python Confusion Matrix Visualization Python Python Algorithms Python Modules List Difference between Python 2 and Python 3 Is Python Case Sensitive Method Overloading in Python Python Arithmetic Operators Assignment Operators in Python Is Python Object Oriented Programming language Division in Python Python exit commands Continue And Pass Statements In Python Colors In Python Convert String Into Int In Python Convert String To Binary In Python Convert Uppercase To Lowercase In Python Convert XML To JSON In Python Converting Set To List In Python Covariance In Python CSV Module In Python Decision Tree In Python Difference Between Yield And Return In Python Dynamic Typing In Python

How to

How to Substring a String in Python How to Iterate through a Dictionary in Python How to convert integer to float in Python How to reverse a string in Python How to take input in Python How to install Python in Windows How to install Python in Ubuntu How to install PIP in Python How to call a function in Python How to download Python How to comment multiple lines in Python How to create a file in Python How to create a list in Python How to declare array in Python How to clear screen in Python How to convert string to list in Python How to take multiple inputs in Python How to write a program in Python How to compare two strings in Python How to create a dictionary in Python How to create an array in Python How to update Python How to compare two lists in Python How to concatenate two strings in Python How to print pattern in Python How to check data type in python How to slice a list in python How to implement classifiers in Python How To Print Colored Text in Python How to develop a game in python How to print in same line in python How to create a class in python How to find square root in python How to import numy in python How to import pandas in python How to uninstall python How to upgrade PIP in python How to append a string in python How to open a file in python How to Open a file in python with Path How to run a Python file in CMD How to change the names of Columns in Python How to Concat two Dataframes in Python How to Iterate a List in Python How to learn python Online How to Make an App with Python

Sorting

Python Sort List Sort Dictionary in Python Python sort() function Python Bubble Sort

Programs

Factorial Program in Python Prime Number Program in Python Fibonacci Series Program in Python Leap Year Program in Python Palindrome Program in Python Check Palindrome In Python Calculator Program in Python Armstrong Number Program in Python Python Program to add two numbers Anagram Program in Python Even Odd Program in Python GCD Program in Python Python Exit Program Python Program to check Leap Year Operator Overloading in Python Pointers in Python Python Not Equal Operator Raise Exception in Python Salary of Python Developers in India What is a Script in Python

Python Identifiers

Identifiers in Python

User-defined names are identifiers in Python that are used to name variables, functions, classes, modules, and other things. You can create Python identifiers using these rules:

  • As an identifier name, you can't utilize reserved keywords. In Python, keywords are reserved names that are built-in. We can't use them as identifier names since they have a special significance.

Note: If you want to see a list of all the keywords, type "help()" and then "keywords" in your Python shell to get a list of all Python keywords.

  • Small case (a-z), upper case (A-Z), digits (0-9), and underscore (_) can all be used in a Python identifier.
    i.e., These are the valid characters.
    • Lowercase letters (a to z)
    • Uppercase letters (A to Z)
    • Digits (0 to 9)
    • Underscore (_)
    • The name of the identifier must not begin with a digit.
    • Only digits are allowed in a Python identifier.
    • The name of a Python identifier can begin with an underscore. It’s the only special symbol that can be used over there. (!, @, #, $, %, etc.) are all invalid symbols.
    • The length of the identification name is unrestricted. Of course, it cannot exceed the available memory; nonetheless, the PEP-8 standards regulation specifies that a line should not contain more than 79 characters.
    • The names of Python identifiers are case sensitive.

Example of Python Valid Identifiers:

  • gb20r ->  is made up of of letters and digits.
  • abcd_E-> contains all the acceptable characters.
  • _-> unexpectedly, although Yes, the underscore character is a recognized identifier.
  • _avc-> an identifier that begins with an underscore.

Examples of Invalid Identifiers in Python:

  • 9967-> identifier can't start with digits.
  • A#+y -> an underscore is the only special character allowed.
  • For ->  a reserved keyword

How to Know if a String is a Valid Identifier

To determine whether an identifier name is valid, we can utilize the string isidentifier() function. This technique, however, does not take reserved keywords into account. As a result, we can use this function in conjunction with keyword.iskeyword() to determine whether or not the name is valid.

Syntax

string.isidentifier()

Parameter Values: No parameters.

Example:

a = "MyFilebook"
b = "Dasging8002"
c = "2bringmehome"
d = "my dream dance"


print(a.isidentifier())
print(b.isidentifier())
print(c.isidentifier())
print(d.isidentifier())

Output:

Identifiers in Python

Best Practices for Naming Python Identifiers

  • The first letter of each class should be capitalized. For example, "person," "employee," and so on.
  • If the class name contains multiple words, the initial character of each word should be capitalised. For instance, EmployeeData, StringUtils, and so on.
  • Variables, functions, and module names should all be written in small letters. For instance, collections, foo(), and so on.
  • If the names of variables, functions, or modules contain multiple words, use an underscore to separate them. For instance, is empty(), employee object, and so on.
  • You can start the names of private variables with an underscore.
  • In the identifier name, avoid using underscore as the first and last character. 
    Python's built-in types make use of it.
  • If the identifier contains two underscores at the beginning and end, it is a language-defined special name. 
  • As a result, two underscores at the beginning and end of the identifier name should be avoided.
  • To clarify their aim, keep identifier names meaningful. For instance, phone number, is uppercase, and so on.
  • It's preferable to start a function's name with "is" if it returns a boolean value. For instance, isidentifier, iskeyword, and so on.
  • The length of the identifier name is unrestricted. However, make it brief and to-the-point. 
    The employee object first name, for example, may be renamed emp first name.

Python Identifiers Reserved Classes

Some Python classes have specific meanings, and we employ patterns of preceding and trailing underscores to identify them.

  1. (_*) is a single leading underscore
    In the interactive interpreter, this identifier is used to hold the result of the most recent evaluation. The __builtin__ module stores these findings. These are private variables, and "from module import *" does not import them.
  • (__*__) Double leading and trailing underscores
    This syntax is only used for system-defined names. The interpreter and its implementations define them. Using this standard to define additional names is not encouraged.
  • Double underscores in front (__ *)
    Manipulation of class-private names: These category names are used in the context of class definitions. They've been rewritten to utilize a mangled form and avoid name collisions between base and derived classes' private variables.

Conclusion

User-defined names are identifiers in Python. 

In a Python application, they are used to define entities. 

To hint at the use of the identifier, we should utilise proper names. 

Make it simple and meaningful by following the rule "keep things simple and 

meaningful".



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