"Python variables store values, support types, reassignment, and dynamic typing." смотреть онлайн

What is a Variable?
In programming, a variable is a named storage location used to store data or values. It acts as a placeholder that allows you to manipulate and reference data throughout your program.

Declaring and Assigning Variables:
In Python, declaring a variable is as simple as giving it a name and assigning a value to it using the assignment operator =.


# Syntax: variable_name = value
age = 25
name = "John"
Rules for Naming Variables:

Variable names can consist of letters, digits, and underscores.
They must start with a letter or an underscore.
Variable names are case-sensitive (e.g., age and Age are different variables).
Python keywords (reserved words like if, else, while, etc.) cannot be used as variable names.
Data Types:
Variables can hold different types of data, such as numbers, strings, and more. Python has several built-in data types:

Integers (int): Whole numbers without decimal points.

age = 25
Floating-Point Numbers (float): Numbers with decimal points.
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height = 5.9
Strings (str): Sequence of characters enclosed in single or double quotes.

name = "John"
message = 'Hello, world!'
Booleans (bool): Represents either True or False.

is_student = True
is_employee = False
Variable Reassignment:
You can change the value stored in a variable by assigning a new value to it.


age = 25
age = 30 # Reassigning the value of 'age'
Multiple Assignments:
Python allows you to assign multiple variables in a single line.


x, y, z = 10, 20, 30
Dynamic Typing:
Python is dynamically typed, meaning you don't need to declare the type of a variable explicitly. The interpreter determines the type based on the assigned value.

Type Conversion (Casting):
You can convert between different data types using type casting functions:


# Converting int to float
x = 5
y = float(x)

# Converting float to int
z = int(3.14)

# Converting int to string
num = 123
num_str = str(num)
Print Variable Values:
To display the value of a variable, you can use the print() function.


name = "Alice"
print(name) # Output: Alice
Variables are fundamental building blocks in programming. They allow you to store and manipulate data dynamically, making your programs more versatile and powerful.