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2.4 Introduction to Python Syntax

Python is a powerful, high-level programming language known for its simplicity and readability. It is widely used in various fields such as web development, data science, and automation. Python's syntax is clear and easy to learn, making it a great choice for beginners.

2.4.1. Comments​

In Python, comments are written using the # symbol. Comments are ignored by the Python interpreter and are used to explain the code.

# This is a single-line comment
print("Hello, World!")  # This is an inline comment

2.4.2. Indentation​

Unlike many programming languages that use braces { } to define blocks of code, Python uses indentation. It is important to consistently use spaces (usually 4 spaces) or tabs for indentation. The line that introduces a new block of code should always end with :, and the next line should then always have its indentation (4 spaces / tab) increased by 1. There is no symbol that indicates the end of a code block, the block simply ends when the indentation is decreased.

if a > 5:
    print("This is indented")  # This block will run if the condition is True
else:
    print("This is also indented") # Will run if the condition is False


    print("This line is part of the else block")

print("This is not indented") # Will run afterwards, regardless of condition

2.4.3. Variables​

Python is dynamically typed, which means you don't need to declare the type of a variable before using it. A variable is simply created by assigning a value.

x = 10  # Creating a variable and assigning it a value
y = 5

2.4.4. Basic Operators​

Python supports basic mathematical operations like addition, subtraction, multiplication, and division.

x = 10
y = 5

sum = x + y          # Addition
difference = x - y   # Subtraction
product = x * y      # Multiplication
quotient = x / y     # Division

2.4.5. Control Flow​

Core functionality for controlling the logical flow of your program.

if Statement​

The if statement checks if a condition is true and executes a block of code if it is.

if x > 5:
    print("x is greater than 5")

else and elif​

else runs when the if condition is false, and elif allows checking additional conditions.

if x > 5:
    print("x is greater than 5")
elif x == 5:
    print("x is equal to 5")
else:
    print("x is less than 5")

Loops​

for Loop A for loop is used to iterate over a sequence (like a list or range).

for i in range(5):
    print(i)  # Prints numbers 0 to 4

while Loop​

A while loop runs as long as the condition is true.

count = 0
while count < 5:
    print(count)
    count += 1

2.4.6. Functions​

Functions in Python are defined using the def keyword. Functions help organize code into reusable blocks. The definition of functions should always end with parentheses (). The parentheses may contain one or more parameters that serve as input data for the function.

def greet():
    print("Hello!")

def greet_2(name):
    print("Hello", name, "!")

greet()  # Calling the function
greet_2("Bob")

2.4.7. Basic Data Structures​

Lists​

Lists are used to store multiple items. They are defined with square brackets [].

fruits = ["apple", "banana", "cherry"]
print(fruits[0])  # Accessing the first item in the list

Dictionaries​

Dictionaries store data in key-value pairs, defined with curly braces {}.

person = {"name": "Alice", "age": 25}
print(person["name"])  # Accessing the value by key