Master Python from Basics to Advanced

 

Learn Python step-by-step with practical examples, essential concepts, coding tips, and best practices. Perfect for beginners who want to build strong programming skills and start coding with confidence!

Python Programming

1. Introduction to Python

Python is a high-level, general-purpose programming language known for its simple syntax, readability, flexibility, and large collection of libraries.

Python was created by Guido van Rossum. Development began in the late 1980s, and Python was first released publicly in 1991.

Python is used for:

  • Software development
  • Web development
  • Data analysis
  • Artificial Intelligence
  • Machine Learning
  • Automation
  • Scientific computing
  • Cybersecurity
  • Desktop applications
  • Game development
  • Network programming
  • Database applications

Simple Python Program

print("Hello, World!")

Output

Hello, World!


2. History of Python

Python was designed by Guido van Rossum as a successor to the ABC programming language.

Important milestones

Year

Development

1989

Python development began

1991

Python 0.9.0 released

1994

Python 1.0 released

2000

Python 2.0 released

2008

Python 3.0 released

Present

Python 3.x is the actively used major version

Python's name was inspired by the British comedy group Monty Python, rather than the snake.


3. Characteristics of Python

Python has several important characteristics.

3.1 High-Level Language

Python hides many low-level hardware details from programmers.

Example:

a = 10

b = 20

print(a + b)

The programmer does not need to manage memory addresses manually.

3.2 Interpreted

Python is commonly described as an interpreted language because Python programs are executed through the Python interpreter.

Modern Python implementations internally compile source code into bytecode, which is then executed by the Python virtual machine.

3.3 Dynamically Typed

The programmer does not normally need to declare a variable's data type.

x = 10

x = "Python"

The same variable name can refer to objects of different types at different times.

3.4 Object-Oriented

Python supports object-oriented programming.

It provides:

  • Classes
  • Objects
  • Inheritance
  • Encapsulation
  • Polymorphism
  • Abstraction

3.5 Portable

Python programs can generally run on different operating systems with little or no modification.

Examples:

  • Windows
  • Linux
  • macOS

3.6 Open Source

Python is freely available and its source code can be examined and modified under its open-source license.

3.7 Extensible

Python can work with code written in other languages such as C and C++.

3.8 Large Standard Library

Python provides many built-in modules for:

  • Mathematics
  • File handling
  • Dates and times
  • Networking
  • Operating-system operations
  • Data processing
  • Internet protocols

4. Advantages of Python

Major advantages

  1. Easy syntax
  2. Easy to learn
  3. Highly readable
  4. Free and open source
  5. Cross-platform
  6. Large standard library
  7. Huge ecosystem of third-party packages
  8. Supports multiple programming paradigms
  9. Useful for rapid development
  10. Large developer community
  11. Excellent for automation
  12. Widely used in AI and data science

5. Limitations of Python

Python also has some disadvantages.

5.1 Execution Speed

Python is generally slower than compiled languages such as C and C++ for many CPU-intensive tasks.

5.2 Memory Consumption

Python programs can consume relatively more memory.

5.3 Mobile Development

Python is not generally the first choice for native mobile application development.

5.4 Runtime Type Errors

Because Python uses dynamic typing, some type-related errors may appear only when a particular part of the program runs.

5.5 Global Interpreter Lock

The standard CPython implementation has a Global Interpreter Lock (GIL), which historically limits simultaneous execution of Python bytecode by multiple threads in many CPU-bound workloads.


6. Python Installation

To program in Python, you generally need:

  1. Python interpreter
  2. Code editor or IDE

Common development environments include:

  • IDLE
  • Visual Studio Code
  • PyCharm
  • Jupyter Notebook
  • Other editors supporting Python

After installing Python, you can check the version using:

python --version

or, on some systems:

python3 --version


7. Python Program Structure

A simple Python program:

name = "Ram"

age = 20

 

print("Name:", name)

print("Age:", age)

Python uses indentation to define blocks of code.

Example:

age = 20

 

if age >= 18:

    print("Adult")

The indented statement belongs to the if block.


8. Python Comments

Comments are explanatory notes that are ignored by the Python interpreter.

Single-line comment

# This is a comment

print("Hello")

Multi-line documentation/string

Python does not have a separate multiline-comment syntax, but triple-quoted strings are commonly used for documentation:

"""

This is a multi-line string.

It can be used as documentation.

"""


9. Tokens in Python

A token is the smallest meaningful unit of a Python program.

Major types include:

  1. Keywords
  2. Identifiers
  3. Literals
  4. Operators
  5. Delimiters

Example:

x = 10 + 5

Here:

  • x → identifier
  • = → assignment operator
  • 10 → integer literal
  • + → arithmetic operator
  • 5 → integer literal

10. Python Keywords

Keywords are reserved words that have special meaning.

Examples include:

if

else

elif

for

while

break

continue

def

return

class

try

except

finally

import

from

as

and

or

not

True

False

None

They cannot normally be used as ordinary variable names.


11. Identifiers

An identifier is the name given to a variable, function, class, module, etc.

Examples:

name = "Ram"

age = 20

student_marks = 85

Rules for identifiers

  • Can contain letters, digits, and underscore.
  • Cannot begin with a digit.
  • Cannot contain spaces.
  • Cannot be a Python keyword.
  • Python is case-sensitive.

Valid:

name

student_name

marks1

_total

Invalid:

1name

student name

class


12. Variables

A variable is a name that refers to an object/value.

name = "Sita"

age = 18

marks = 85.5

Python automatically determines the type of the assigned object.

x = 100

print(type(x))

Output:

<class 'int'>


13. Constants

Python does not enforce constants using a special keyword.

Programmers commonly use uppercase names to indicate that a value should not be changed.

PI = 3.14159

MAX_MARKS = 100

This is a naming convention rather than strict enforcement by Python.


14. Data Types

Python provides several built-in data types.

Main categories

Category

Examples

Numeric

int, float, complex

Boolean

bool

Text

str

Sequence

list, tuple, range

Mapping

dict

Set

set, frozenset

Binary

bytes, bytearray

Special

NoneType


15. Integer

Integers are whole numbers.

x = 100

y = -25

z = 0

Python integers can represent arbitrarily large values subject to available memory.


16. Floating-Point Numbers

Floating-point values represent numbers with decimal parts.

price = 99.50

temperature = 36.5


17. Complex Numbers

Complex numbers contain real and imaginary components.

z = 3 + 4j

print(z)

Output:

(3+4j)


18. Boolean Data Type

Boolean values are:

True

False

Example:

is_student = True

Booleans are commonly used in conditions.


19. String

A string is a sequence of characters.

name = "Python"

Strings can use single or double quotes:

name = 'Python'

language = "Python"

String operations

text = "Python"

 

print(text[0])

print(text[1])

print(len(text))

Output:

P

y

6


20. String Slicing

Slicing extracts part of a string.

text = "Python Programming"

 

print(text[0:6])

Output:

Python

Other examples:

text[:6]

text[7:]

text[::2]

text[::-1]


21. Common String Methods

text = "hello python"

 

print(text.upper())

print(text.lower())

print(text.title())

print(text.replace("python", "world"))

Common methods:

  • upper()
  • lower()
  • title()
  • capitalize()
  • strip()
  • replace()
  • split()
  • join()
  • find()
  • startswith()
  • endswith()

22. Type Conversion

Type conversion means changing one data type into another.

x = "100"

 

number = int(x)

print(number)

Common functions:

int()

float()

str()

bool()

list()

tuple()

set()

Example:

a = 10

b = 5.5

 

print(float(a))

print(int(b))


23. Input Function

The input() function accepts user input.

name = input("Enter your name: ")

print("Hello", name)

Important: input() normally returns a string.

For numeric input:

age = int(input("Enter your age: "))

print(age)


24. Output Function

The print() function displays output.

print("Hello")

print(10)

print(10 + 20)

Multiple values:

name = "Ram"

age = 20

 

print("Name:", name, "Age:", age)


25. Operators in Python

Operators perform operations on values.

Major categories:

  1. Arithmetic
  2. Comparison
  3. Assignment
  4. Logical
  5. Bitwise
  6. Membership
  7. Identity

26. Arithmetic Operators

Operator

Meaning

+

Addition

-

Subtraction

*

Multiplication

/

Division

%

Modulus

//

Floor division

**

Exponentiation

Example:

a = 10

b = 3

 

print(a + b)

print(a - b)

print(a * b)

print(a / b)

print(a % b)

print(a // b)

print(a ** b)


27. Comparison Operators

Comparison operators return Boolean values.

==    Equal

!=    Not equal

>     Greater than

<     Less than

>=    Greater than or equal

<=    Less than or equal

Example:

a = 10

b = 20

 

print(a < b)

Output:

True


28. Logical Operators

Python has three main logical operators:

and

or

not

Example:

age = 20

 

print(age >= 18 and age <= 60)


29. Assignment Operators

Examples:

=

+=

-=

*=

/=

%=

**=

//=

Example:

x = 10

x += 5

 

print(x)

Output:

15


30. Membership Operators

Membership operators are:

in

not in

Example:

fruits = ["Apple", "Mango", "Banana"]

 

print("Mango" in fruits)

Output:

True


31. Identity Operators

Identity operators:

is

is not

They test whether two references refer to the same object, rather than merely whether their values are equal.

a = [1, 2]

b = a

 

print(a is b)


32. Conditional Statements

Conditional statements allow a program to make decisions.

if

age = 20

 

if age >= 18:

    print("Adult")

if-else

age = 15

 

if age >= 18:

    print("Adult")

else:

    print("Minor")

if-elif-else

marks = 75

 

if marks >= 80:

    print("A")

elif marks >= 60:

    print("B")

elif marks >= 40:

    print("C")

else:

    print("Fail")


33. Nested if

An if statement can contain another if.

age = 20

citizen = True

 

if age >= 18:

    if citizen:

        print("Eligible")


34. Loops

Loops execute a block repeatedly.

Python mainly provides:

  • for
  • while

35. For Loop

for i in range(1, 6):

    print(i)

Output:

1

2

3

4

5


36. While Loop

i = 1

 

while i <= 5:

    print(i)

    i += 1


37. Range Function

range() generates a sequence of numbers.

range(stop)

range(start, stop)

range(start, stop, step)

Example:

for i in range(2, 10, 2):

    print(i)

Output:

2

4

6

8


38. Break Statement

break terminates the loop.

for i in range(10):

    if i == 5:

        break

    print(i)


39. Continue Statement

continue skips the current iteration.

for i in range(5):

    if i == 2:

        continue

    print(i)


40. Pass Statement

pass does nothing and is used as a placeholder.

for i in range(5):

    pass


41. Lists

A list is an ordered, mutable collection.

students = ["Ram", "Sita", "Hari"]

Lists can contain different data types:

data = [10, "Python", 5.5, True]


42. List Indexing

fruits = ["Apple", "Banana", "Mango"]

 

print(fruits[0])

print(fruits[-1])

Output:

Apple

Mango


43. List Methods

Common methods:

append()

extend()

insert()

remove()

pop()

clear()

index()

count()

sort()

reverse()

copy()

Example:

numbers = [3, 1, 2]

 

numbers.append(4)

numbers.sort()

 

print(numbers)

Output:

[1, 2, 3, 4]


44. Tuples

A tuple is an ordered and immutable collection.

numbers = (10, 20, 30)

Because tuples are immutable, their elements cannot normally be changed after creation.


45. Sets

A set is an unordered collection of unique elements.

numbers = {1, 2, 3, 3}

 

print(numbers)

Duplicate values are removed.

Sets support operations such as:

  • Union
  • Intersection
  • Difference
  • Symmetric difference

Example:

a = {1, 2, 3}

b = {3, 4, 5}

 

print(a | b)

print(a & b)


46. Dictionary

A dictionary stores data as key-value pairs.

student = {

    "name": "Ram",

    "age": 20,

    "marks": 85

}

Accessing data:

print(student["name"])

Adding data:

student["address"] = "Mahottari"


47. Dictionary Methods

Common methods:

keys()

values()

items()

get()

update()

pop()

clear()

Example:

student = {"name": "Ram", "age": 20}

 

print(student.keys())

print(student.values())


48. Functions

A function is a reusable block of code.

Syntax:

def function_name(parameters):

    statements

Example:

def greet():

    print("Hello")

 

greet()


49. Function Parameters

def greet(name):

    print("Hello", name)

 

greet("Ram")


50. Return Statement

def add(a, b):

    return a + b

 

result = add(10, 20)

print(result)

Output:

30


51. Types of Function Arguments

Python supports:

  • Positional arguments
  • Keyword arguments
  • Default arguments
  • Variable-length arguments

Example:

def greet(name="User"):

    print("Hello", name)

 

greet()

greet("Ram")


52. *args

*args allows a function to receive multiple positional arguments.

def total(*numbers):

    return sum(numbers)

 

print(total(10, 20, 30))


53. **kwargs

**kwargs allows multiple keyword arguments.

def student_info(**data):

    print(data)

 

student_info(name="Ram", age=20)


54. Lambda Function

A lambda is a small anonymous function.

square = lambda x: x * x

 

print(square(5))

Output:

25


55. Scope of Variables

Local Variable

Created inside a function.

def test():

    x = 10

Global Variable

Created outside functions.

x = 10

 

def test():

    print(x)

Python also provides global and nonlocal statements for specific scope-management cases.


56. Recursion

Recursion occurs when a function calls itself.

Example:

def factorial(n):

    if n == 0:

        return 1

    return n * factorial(n - 1)

 

print(factorial(5))

Output:

120


57. Object-Oriented Programming

Python supports OOP.

Important concepts:

  1. Class
  2. Object
  3. Constructor
  4. Inheritance
  5. Encapsulation
  6. Polymorphism
  7. Abstraction

58. Class

A class is a blueprint for creating objects.

class Student:

    name = "Ram"


59. Object

An object is an instance of a class.

class Student:

    name = "Ram"

 

student1 = Student()

 

print(student1.name)


60. Constructor

The __init__() method is commonly used to initialize an object.

class Student:

 

    def __init__(self, name, age):

        self.name = name

        self.age = age

 

student = Student("Ram", 20)

 

print(student.name)

print(student.age)


61. Inheritance

Inheritance allows one class to inherit attributes and methods from another class.

class Animal:

    def speak(self):

        print("Animal sound")

 

class Dog(Animal):

    pass

 

dog = Dog()

dog.speak()


62. Polymorphism

Polymorphism means that the same interface or method name can behave differently for different objects.

class Dog:

    def sound(self):

        print("Bark")

 

class Cat:

    def sound(self):

        print("Meow")

 

for animal in [Dog(), Cat()]:

    animal.sound()


63. Encapsulation

Encapsulation involves keeping data and the methods operating on it together and controlling access to internal implementation details.

Python uses naming conventions such as:

_name

__name

A double underscore triggers name mangling in many class contexts.


64. Modules

A module is a Python file containing definitions and statements.

Example:

import math

 

print(math.sqrt(25))


65. Common Built-in Modules

Examples include:

  • math
  • random
  • datetime
  • os
  • sys
  • json
  • statistics
  • re
  • time

Example:

import math

 

print(math.pi)

print(math.sqrt(16))


66. Import Statement

import math

Specific import:

from math import sqrt

 

print(sqrt(25))

Alias:

import math as m

 

print(m.sqrt(25))


67. Packages

A package is a way of organizing related Python modules into a directory structure.

For example, a project might have:

project/

    main.py

    utilities/

        __init__.py

        calculation.py

        display.py


68. Exception Handling

Exceptions are runtime events that can interrupt normal program execution.

Python uses:

try

except

else

finally

Example:

try:

    x = int(input("Enter a number: "))

    print(10 / x)

 

except ValueError:

    print("Please enter a valid number.")

 

except ZeroDivisionError:

    print("Cannot divide by zero.")


69. Finally Block

finally executes whether or not an exception occurs.

try:

    print("Processing")

finally:

    print("Finished")


70. Raising Exceptions

Programmers can deliberately raise exceptions.

age = -5

 

if age < 0:

    raise ValueError("Age cannot be negative")


71. File Handling

Python provides the open() function for file operations.

Common modes:

Mode

Meaning

r

Read

w

Write

a

Append

x

Create

b

Binary

t

Text


72. Reading a File

with open("data.txt", "r") as file:

    content = file.read()

 

print(content)

The with statement helps ensure that the file is properly closed.


73. Writing to a File

with open("data.txt", "w") as file:

    file.write("Python Programming")


74. Appending to a File

with open("data.txt", "a") as file:

    file.write("\nNew line")


75. CSV Files

Python provides the csv module.

import csv

 

with open("students.csv", newline="") as file:

    reader = csv.reader(file)

 

    for row in reader:

        print(row)


76. JSON

JSON is commonly used for exchanging structured data.

import json

 

data = {

    "name": "Ram",

    "age": 20

}

 

text = json.dumps(data)

print(text)

To convert JSON text back into a Python object:

data = json.loads(text)

print(data["name"])


77. List Comprehension

List comprehension provides a concise way to create lists.

Traditional:

squares = []

 

for i in range(1, 6):

    squares.append(i * i)

List comprehension:

squares = [i * i for i in range(1, 6)]


78. Dictionary Comprehension

squares = {x: x*x for x in range(1, 6)}

 

print(squares)


79. Iterators

An iterator is an object that produces values one at a time.

Important functions:

iter()

next()

Example:

numbers = iter([10, 20, 30])

 

print(next(numbers))

print(next(numbers))


80. Generators

Generators produce values lazily using yield.

def numbers():

    yield 1

    yield 2

    yield 3

 

for number in numbers():

    print(number)

Generators are useful when working with large sequences because values can be produced one at a time.


81. Decorators

A decorator is a mechanism for modifying or extending the behavior of a function or class without changing its original source code.

Basic example:

def decorator(function):

    def wrapper():

        print("Before function")

        function()

        print("After function")

    return wrapper

 

@decorator

def hello():

    print("Hello")

 

hello()


82. Regular Expressions

Python provides the re module for pattern matching.

import re

 

text = "My phone number is 12345"

 

result = re.search(r"\d+", text)

 

if result:

    print(result.group())


83. Date and Time

Python provides the datetime module.

from datetime import datetime

 

now = datetime.now()

 

print(now)

Specific components:

print(now.year)

print(now.month)

print(now.day)


84. Random Numbers

The random module generates pseudo-random values.

import random

 

number = random.randint(1, 10)

print(number)


85. Math Module

import math

 

print(math.sqrt(25))

print(math.factorial(5))

print(math.pi)


86. Object Identity and Equality

There is an important difference between == and is.

==

Checks whether values compare equal.

a = [1, 2]

b = [1, 2]

 

print(a == b)

Output:

True

is

Checks object identity.

print(a is b)

This is normally False because they are separate list objects.


87. Python Indentation

Indentation is fundamental to Python syntax.

Correct:

if True:

    print("Correct")

Incorrect:

if True:

print("Incorrect")

Python generally uses four spaces for each indentation level.


88. Python's None

None represents the absence of a value.

result = None

 

print(result)

It is different from:

0

False

""


89. pass, break, and continue

Statement

Purpose

pass

Does nothing; placeholder

break

Terminates loop

continue

Skips current iteration


90. Python Package Management

Python packages are commonly installed using pip.

Example:

pip install requests

Upgrade:

pip install --upgrade requests

Remove:

pip uninstall requests

List installed packages:

pip list


91. Virtual Environment

A virtual environment isolates project dependencies.

Create:

python -m venv myenv

Activation commands depend on the operating system and shell.

This is useful because different projects may require different package versions.


92. Python and Databases

Python can work with many databases.

Examples:

  • SQLite
  • MySQL
  • PostgreSQL
  • Microsoft SQL Server
  • Oracle Database

SQLite example:

import sqlite3

 

connection = sqlite3.connect("school.db")

 

cursor = connection.cursor()

 

cursor.execute("""

CREATE TABLE IF NOT EXISTS students (

    id INTEGER PRIMARY KEY,

    name TEXT,

    marks INTEGER

)

""")

 

connection.commit()

connection.close()


93. Python for Web Development

Popular Python web frameworks include:

Django

A powerful framework suitable for larger web applications.

Flask

A lightweight framework that provides flexibility.

FastAPI

Designed for building modern APIs with strong support for type hints and asynchronous programming.


94. Python for Data Science

Python is extremely popular in data science.

Important libraries:

NumPy

Used for numerical computing and multidimensional arrays.

Pandas

Used for data manipulation and analysis.

Matplotlib

Used for creating charts and graphs.

Seaborn

Used for statistical data visualization.

Example:

import pandas as pd

 

data = pd.DataFrame({

    "Name": ["Ram", "Sita"],

    "Marks": [80, 90]

})

 

print(data)


95. Python for Artificial Intelligence

Python is widely used in AI because of its libraries and ecosystem.

Important tools include:

  • NumPy
  • Pandas
  • Scikit-learn
  • TensorFlow
  • PyTorch
  • OpenCV

Applications include:

  • Image recognition
  • Natural language processing
  • Recommendation systems
  • Speech processing
  • Predictive modeling
  • Computer vision

96. Python for Machine Learning

A typical machine-learning workflow may involve:

  1. Collecting data
  2. Cleaning data
  3. Exploring data
  4. Preparing features
  5. Training a model
  6. Evaluating the model
  7. Improving the model
  8. Deploying the model

Scikit-learn provides many classical machine-learning algorithms.


97. Python for Automation

Python can automate repetitive tasks.

Examples:

  • Renaming files
  • Processing documents
  • Generating reports
  • Reading spreadsheets
  • Sending automated notifications
  • Data processing
  • System administration

Example:

import os

 

for filename in os.listdir("."):

    print(filename)


98. Python for Networking

Python provides modules and libraries for network programming.

Examples:

  • socket
  • http
  • urllib
  • requests

Basic example:

import socket

 

hostname = socket.gethostname()

print(hostname)


99. Python for GUI Development

Python can create graphical user interfaces.

Popular options include:

  • Tkinter
  • PyQt
  • PySide
  • Kivy

Simple Tkinter example:

import tkinter as tk

 

window = tk.Tk()

window.title("My Application")

 

label = tk.Label(window, text="Hello Python")

label.pack()

 

window.mainloop()


100. Python Programming Paradigms

Python supports multiple programming styles.

Procedural Programming

Programs are organized around procedures/functions.

Object-Oriented Programming

Programs are organized around classes and objects.

Functional Programming

Python supports concepts such as:

  • Lambda functions
  • map()
  • filter()
  • reduce()
  • Higher-order functions
  • Comprehensions

Example:

numbers = [1, 2, 3, 4]

 

squares = list(map(lambda x: x*x, numbers))

 

print(squares)


101. Python Memory Management

Python automatically manages memory.

The interpreter keeps track of objects and can reclaim memory that is no longer needed.

Important concepts include:

  • References
  • Object allocation
  • Reference counting in CPython
  • Garbage collection

Programmers generally do not manually allocate and free memory as they do in languages such as C.


102. Garbage Collection

Python includes automatic garbage collection for managing certain objects, particularly reference cycles.

Example concept:

a = [1, 2, 3]

a = None

When an object is no longer reachable, Python can eventually reclaim the memory associated with it.


103. Python Bytecode

When Python source code is executed in CPython, it is generally compiled into an intermediate representation called bytecode.

Conceptually:

Python Source Code

        ↓

Python Compiler

        ↓

Bytecode

        ↓

Python Virtual Machine

        ↓

Execution

Implementation details can vary between Python implementations and versions.


104. Python Interpreter

The interpreter executes Python programs.

Common implementations include:

  • CPython — the reference implementation and most widely used
  • PyPy — alternative implementation with a JIT compiler
  • Jython — Python implementation for the Java platform
  • IronPython — Python implementation for the .NET ecosystem

105. Error Types

Python programs can encounter different kinds of errors.

Syntax Error

Occurs when Python syntax is invalid.

if True

    print("Hello")

NameError

Occurs when an undefined name is referenced.

print(value)

TypeError

Occurs when an operation is applied to an inappropriate type.

"10" + 5

ValueError

Occurs when a value has the correct general type but an inappropriate value.

int("hello")

IndexError

Occurs when a sequence index is outside its valid range.

items = [1, 2]

print(items[5])

KeyError

Occurs when a dictionary key does not exist.

data = {"name": "Ram"}

print(data["age"])


106. Debugging

Debugging means identifying and correcting errors in a program.

Common approaches:

  • Read error messages
  • Use print() for simple inspection
  • Use an IDE debugger
  • Check variables
  • Test smaller sections
  • Use logging
  • Write automated tests

107. Python Testing

Testing checks whether software behaves as expected.

Python provides the built-in unittest framework.

Example:

import unittest

 

def add(a, b):

    return a + b

 

class TestAdd(unittest.TestCase):

 

    def test_add(self):

        self.assertEqual(add(2, 3), 5)

 

if __name__ == "__main__":

    unittest.main()

Another popular testing framework is pytest.


108. Python Coding Style

Python programmers commonly follow PEP 8, the Python style guide.

Good practices include:

  • Use meaningful variable names.
  • Use consistent indentation.
  • Keep functions focused.
  • Add useful documentation.
  • Avoid unnecessary complexity.
  • Follow consistent naming conventions.

Example:

student_name = "Ram"

total_marks = 450

This is generally clearer than:

sn = "Ram"

tm = 450


109. Complete Beginner Example

name = input("Enter your name: ")

marks = float(input("Enter your marks: "))

 

if marks >= 80:

    grade = "A"

elif marks >= 60:

    grade = "B"

elif marks >= 40:

    grade = "C"

else:

    grade = "F"

 

print("Name:", name)

print("Marks:", marks)

print("Grade:", grade)

Working of the program

  1. The user enters a name.
  2. The user enters marks.
  3. float() converts the marks into a number.
  4. if-elif-else determines the grade.
  5. print() displays the result.

110. Example: Simple Calculator

a = float(input("Enter first number: "))

operator = input("Enter operator (+, -, *, /): ")

b = float(input("Enter second number: "))

 

if operator == "+":

    result = a + b

elif operator == "-":

    result = a - b

elif operator == "*":

    result = a * b

elif operator == "/":

    if b != 0:

        result = a / b

    else:

        result = "Cannot divide by zero"

else:

    result = "Invalid operator"

 

print("Result:", result)


111. Example: Finding Even and Odd Numbers

number = int(input("Enter a number: "))

 

if number % 2 == 0:

    print("Even number")

else:

    print("Odd number")


112. Example: Finding the Largest Number

a = 10

b = 25

c = 15

 

largest = max(a, b, c)

 

print("Largest:", largest)


113. Example: Factorial

n = int(input("Enter a number: "))

 

factorial = 1

 

for i in range(1, n + 1):

    factorial *= i

 

print("Factorial:", factorial)


114. Example: Multiplication Table

number = int(input("Enter a number: "))

 

for i in range(1, 11):

    print(number, "×", i, "=", number * i)


115. Example: Student Record Using Dictionary

student = {

    "name": "Ram",

    "roll": 15,

    "class": 11,

    "marks": 85

}

 

print("Name:", student["name"])

print("Roll:", student["roll"])

print("Class:", student["class"])

print("Marks:", student["marks"])


116. Python in Computer Operator / Loksewa Preparation

For computer-related competitive examinations, important Python topics include:

Basic concepts

  • Definition of Python
  • History
  • Features
  • Advantages and disadvantages
  • Applications

Syntax

  • Indentation
  • Comments
  • Keywords
  • Identifiers
  • Variables
  • Literals

Data types

  • Integer
  • Float
  • Complex
  • Boolean
  • String
  • List
  • Tuple
  • Set
  • Dictionary

Operators

  • Arithmetic
  • Relational/comparison
  • Logical
  • Assignment
  • Bitwise
  • Membership
  • Identity

Control statements

  • if
  • if-else
  • if-elif-else
  • for
  • while
  • break
  • continue
  • pass

Functions

  • Defining functions
  • Parameters
  • Arguments
  • Return values
  • Lambda functions
  • Recursion
  • *args
  • **kwargs

OOP

  • Class
  • Object
  • Constructor
  • Inheritance
  • Polymorphism
  • Encapsulation
  • Abstraction

Advanced topics

  • Modules
  • Packages
  • Exceptions
  • File handling
  • Regular expressions
  • Iterators
  • Generators
  • Decorators
  • Virtual environments
  • Package management

117. Important Python Differences from C/C++

Feature

Python

C/C++

Typing

Dynamically typed

Primarily statically typed

Memory management

Automatic

More explicit/manual mechanisms

Syntax

Indentation-based blocks

Braces commonly used

Compilation

Typically executed through interpreter/runtime

Typically compiled

Variable declaration

Usually not required

Usually required

Pointer manipulation

Not exposed like C/C++

Supported

Ease of learning

Generally easier

Generally more complex

Execution speed

Generally slower

Generally faster for many compiled workloads


118. Important Python Built-in Functions

Some frequently used built-in functions are:

print()

input()

len()

type()

int()

float()

str()

bool()

list()

tuple()

set()

dict()

range()

sum()

max()

min()

abs()

round()

sorted()

enumerate()

zip()

map()

filter()

open()

Example:

numbers = [10, 20, 30]

 

print(len(numbers))

print(sum(numbers))

print(max(numbers))

print(min(numbers))


119. Important Python Concepts at a Glance

Python

├── Basic Syntax

│   ├── Variables

│   ├── Keywords

│   ├── Identifiers

│   └── Comments

├── Data Types

│   ├── Numbers

│   ├── String

│   ├── List

│   ├── Tuple

│   ├── Set

│   └── Dictionary

├── Operators

│   ├── Arithmetic

│   ├── Comparison

│   ├── Logical

│   ├── Assignment

│   ├── Bitwise

│   ├── Membership

│   └── Identity

├── Control Flow

│   ├── if

│   ├── for

│   ├── while

│   ├── break

│   ├── continue

│   └── pass

├── Functions

│   ├── Parameters

│   ├── Arguments

│   ├── Return

│   ├── Lambda

│   └── Recursion

├── OOP

│   ├── Class

│   ├── Object

│   ├── Inheritance

│   ├── Polymorphism

│   └── Encapsulation

├── Modules & Packages

├── File Handling

├── Exception Handling

└── Libraries & Frameworks

    ├── NumPy

    ├── Pandas

    ├── Django

    ├── Flask

    ├── TensorFlow

    └── PyTorch

Conclusion

Python is a powerful, readable, versatile programming language that can be used from basic programming education to advanced software engineering, data science, artificial intelligence, automation, web development, and scientific computing.

For exam preparation, the highest-priority areas are Python features and history, syntax and indentation, variables and data types, operators, conditional statements, loops, functions, lists/tuples/sets/dictionaries, exception handling, file handling, modules, and object-oriented programming.

  

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