Introduction to Python

Introduction to Python#

Python is a popular, easy-to-learn programming language used in many fields, including web development, data science, and automation. Python has a simple syntax that makes it beginner-friendly, yet it is powerful enough for professional development.

How to Install Python and Run Python Code#

To install Python, follow these steps:

  • Visit python.org and download the latest version of Python.

  • During installation, ensure the checkbox “Add Python to PATH” is checked.

To run Python code:

  • Open the terminal or command prompt.

  • Type python to start the Python interactive shell (REPL).

  • Alternatively, you can save Python scripts in files with the .py extension and run them from the terminal using python filename.py.

Example Code#

You can test your installation by typing this code in Python:

print("Hello, World!")

Expected Output

Hello, World!

Types of Variables#

Variables in Python are used to store data values. The variable name can be anything (as long as it follows naming rules), and the type of the variable is inferred based on the value assigned to it.

Example#

x = 5       # Integer
y = 3.14    # Float
name = "John"  # String
is_active = True  # Boolean

Output

print(type(x))  # <class 'int'>
print(type(y))  # <class 'float'>
print(type(name))  # <class 'str'>
print(type(is_active))  # <class 'bool'>

Types of Data#

Python has several built-in data types. Here are some of the most common:

  • int: Integer numbers (e.g., 1, 100, -5)

  • float: Floating-point numbers (e.g., 3.14, 1.0, -0.1)

  • str: String (text) values (e.g., “hello”, “world”)

  • bool: Boolean values (True or False)

  • list: Ordered collection of items (e.g., [1, 2, 3])

  • tuple: Immutable ordered collection (e.g., (1, 2, 3))

  • dict: Collection of key-value pairs (e.g., {"name": "John", "age": 30})

Example#

my_list = [1, 2, 3, 4]
my_tuple = (5, 6, 7)
my_dict = {"name": "John", "age": 30}

print(type(my_list))  # <class 'list'>
print(type(my_tuple))  # <class 'tuple'>
print(type(my_dict))  # <class 'dict'>

Mathematical Operations#

Python can handle basic mathematical operations:

  • Addition (+)

  • Subtraction (-)

  • Multiplication (*)

  • Division (/)

  • Modulus (remainder) (%)

  • Exponentiation (**)

  • Floor Division (//)

Example#

a = 10
b = 3

print(a + b)  # Addition
print(a - b)  # Subtraction
print(a * b)  # Multiplication
print(a / b)  # Division
print(a % b)  # Modulus
print(a ** b)  # Exponentiation
print(a // b)  # Floor Division

Output

13
7
30
3.3333333333333335
1
1000
3

Conditional Statements (If and Else)#

Conditional statements allow us to execute code based on certain conditions using if, elif, and else.

Example#

age = 18

if age >= 18:
    print("You are an adult.")
else:
    print("You are a minor.")

Output

You are an adult.

Looping (For and While)#

Loops allow us to repeat a block of code multiple times.

For Loop#

Used to iterate over a sequence (like a list or range).

Example#

for i in range(5):
    print(i)

Output

0
1
2
3
4

While Loop#

Repeats as long as a condition is True.

Example#

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

Output

0
1
2
3
4

Functions#

Functions are blocks of reusable code that perform a specific task.

Example#

def greet(name):
    print("Hello, " + name + "!")

greet("Alice")  # Calling the function

Output

Hello, Alice!
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