Learn Python from Scratch: Begin Here

Welcome to Python Basics! This page is your gateway to mastering the fundamentals of Python programming.

Whether you're a beginner looking to start your coding journey or an experienced developer looking to brush up on the basics, this guide is designed to help you understand and work with Python in a clear and easy-to-follow manner. 

Python is a high-level, interpreted, and general-purpose programming language. It emphasizes code readability and simplicity, making it an excellent choice for both beginners and experienced developers.

This article covers the basics of Python, from setting up your environment to writing your first program and understanding key concepts like syntax, control flow, functions, and more. 

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Creating Your Very First Python Program

Before we dive into the more complex features of Python, let's start by writing a simple "Hello World!" program. Python is known for its simplicity, and your first program will show you just how easy it is to get started. 

This program will output: 

This is your very first Python program! It displays a message on the screen using the print() function. Now that you've written your first program, let’s learn how to add comments and more.

Python comments 

In Python, comments are used to explain the code and make it easier to understand. They are ignored by the interpreter and don't affect the execution of the program. 

Single-line Comments: 

Use the # symbol for single-line comments: 

Multi-line Comments: 

For multi-line comments, you can use triple quotes (''' or """): 

Variables in Python 

A variable is a container that stores data. Python is dynamically typed, meaning you don't need to explicitly declare a variable’s type. 

Rules for Python Variables: 

1. A variable name must start with a letter (A-Z, a-z) or an underscore (_). 

2. A variable name cannot start with a number. 

3. A variable name can only contain alphanumeric characters and underscores. 

4. Variable names are case-sensitive. 

Example: 

Output

Data Types in Python 

In Python, data types are used to define the type of a value. Python has several built-in data types, including: 

Integers: Whole numbers, like 5, 100, etc. 

Floats: Decimal numbers, like 3.14, 9.99. 

Strings: Sequences of characters, like "Hello". 

Lists: Ordered collections of items, like [1, 2, 3]. 

Tuples: Immutable ordered collections, like (1, 2, 3). 

Dictionaries: Collections of key-value pairs, like {"name": "John"}. 

Sets: Unordered collections of unique items, like {1, 2, 3}. 

Booleans: True or False. 

Complex Numbers: Numbers with a real and imaginary part, like 3+5j. 

Example: 

Input/Output Python 

The input() function allows you to accept user input. The input is always returned as a string, so you might need to convert it into another data type if required. 

Example: 

Python’s Operators 

Operators are used to perform operations on variables and values. Python supports several types of operators: 

Arithmetic Operators: Used for mathematical calculations like addition, subtraction, etc. 

Logical Operators: Used to perform logical operations such as AND, OR, and NOT. 

Bitwise Operators: Used for bit-level operations. 

Assignment Operators: Used to assign values to variables. 

Python If Else 

The if statement is used for conditional execution of a block of code. The else statement lets you execute a block of code when the if condition is not met. 

Example 1: If-Else Statement 

Output: 

Example 2: If-Elif-Else Ladder 

Python For & While Loops 

For Loop: 

The for loop is used to iterate over a sequence (like a list, tuple, or string). 

Output: 

While Loop: The while loop runs as long as the specified condition is True. 

Output: 

Python Functions 

Functions are blocks of code that perform a specific task. Instead of writing the same code repeatedly, you can define a function and reuse it with different inputs. 

Example of a Simple Function: 

Output: 

Basics Of Python 

Python is an incredibly versatile and widely used programming language, favored for its simplicity, readability, and diverse applications.

Whether you're developing web applications, analyzing data, or building machine learning models, understanding the fundamentals of Python is essential for mastering this powerful language. 

In this section, we will explore the core building blocks of Python. These fundamentals will serve as the foundation for more advanced topics. We’ll cover a wide range of topics, from Python statements to operators, variables, and more. 

Understanding Python Statements 

A statement in Python represents a logical instruction that the interpreter can read and execute. Python statements are classified into two main types: 

Expression Statements: 

An expression is a statement that results in a value. These operations can be mathematical, logical, or even method calls. For example: 

Here, the arithmetic expression (1 + 5) * 3 evaluates to 18, and the function pow(3, 2) evaluates to 9. 

Assignment Statements: 

An assignment statement is used to assign a value to a variable. It’s a fundamental way to store and manipulate data. The basic syntax is: 

variable = expression 

Types of Assignment: 

Value-based Assignment: Python allocates a unique memory location when assigning a value. 

Current Variable Assignment: The new variable references the same memory location. 

Operation-based Assignment: You can also operate on the right-hand side before assignment. 

Multiline Statements: 

Python allows you to extend statements across multiple lines using two methods: 

Implicit Method: Using parentheses, brackets, or braces: 

a = (0 + 1 + 2 + 3 + 4 + 5) 

Explicit Method: Using the continuation character (\): 

a = 0 + 1 + 2 + 3 + 4 + 5 

Indentation: The Python Way 

Unlike many programming languages that use braces {} to define code blocks, Python uses indentation. This makes code more readable and visually structured. Python’s PEP 8 guidelines recommend an indentation of 4 spaces for each level of nesting. 

Example of Indentation: 

Indentation is mandatory, and failing to maintain proper indentation will lead to an IndentationError. 

Conclusion 

Mastering the fundamentals of Python will lay the groundwork for your journey into the vast world of programming.

From understanding core concepts like variables, operators, and statements to leveraging Python's powerful features like docstrings and operators, this knowledge will enable you to write efficient, readable, and scalable code. 

Now, it’s time to start practicing and experimenting with these fundamentals. The more you code, the better you’ll become. Happy coding!