Python Basics

Python Variables

Master Python variable assignment, naming rules, multiple assignment, and variable types.

Python Variables

Variables are containers for storing data values. Unlike other programming languages, Python has no command for declaring a variable. A variable is created the moment you first assign a value to it.

Variable Naming Rules

  • A variable name must start with a letter or underscore
  • A variable name cannot start with a number
  • A variable name can only contain alpha-numeric characters and underscores
  • Variable names are case-sensitive (age, Age, and AGE are three different variables)
  • A variable name cannot be a Python keyword

Multiple Assignment

Python allows you to assign values to multiple variables in one line.

Python as a Dynamic Language

Python is dynamically typed — you can assign different types to the same variable. Use the type() built-in to check a variable's type.

Variable Scope

Variables created outside of functions are global variables. Variables created inside functions are local variables.

Example

python
# Basic assignment
x = 5
name = "DevForge"
is_cool = True

# Multiple assignment
a, b, c = 1, 2, 3
print(a, b, c)  # 1 2 3

# Same value to multiple variables
x = y = z = 0

# Type checking
print(type(x))     # <class 'int'>
print(type(name))  # <class 'str'>
print(type(is_cool))  # <class 'bool'>

# Dynamic typing
var = 42
print(type(var))  # <class 'int'>
var = "now a string"
print(type(var))  # <class 'str'>

# Global vs local
count = 0  # global

def increment():
    global count  # reference global
    count += 1

increment()
print(count)  # 1
Try it yourself — PYTHON