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Variables and Data Types in Python

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In Python, variables are used to store data that can be manipulated and referenced throughout the code. Understanding how to declare and use variables, as well as the different data types available, is fundamental to programming in Python.

Variables

A variable is essentially a name that refers to a value. In Python, you don't need to explicitly declare the type of a variable; the interpreter infers the type from the value assigned to it.


# Assigning values to variables
x = 5
y = "Hello, World!"
z = 3.14
    

# Printing variables
print(x)   # Output: 5
print(y)   # Output: Hello, World!
print(z)   # Output: 3.14

Data Types

Python supports various data types, which can be broadly categorized into several types:

Numeric Types

Integer (int): Whole numbers, positive or negative, without a decimal point.


# Integer data
a = 10
b = -300
print(a)  # Output: 10
print(b)  # Output: -300

Float (float): Numbers with a decimal point.


# Float data
pi = 3.14159
gravity = 9.81
print(pi)  # Output: 3.14159
print(gravity)  # Output: 9.81

Complex (complex): Numbers with a real and an imaginary part.


# Complex data
c = 3 + 4j
print(c)  # Output: (3+4j)
print(c.real)  # Output: 3.0
print(c.imag)  # Output: 4.0

Sequence Types

String (str): A sequence of characters enclosed within single, double, or triple quotes.


# String data
greeting = "Hello"
multi_line = '''This is a
multi-line string.'''
print(greeting)  # Output: Hello
print(multi_line)  
# Output: This is a
#         multi-line string.

List (list): Ordered, mutable collections of items.


# List data
fruits = ["apple", "banana", "cherry"]
fruits.append("date")
print(fruits)  # Output: ['apple', 'banana', 'cherry', 'date']

Tuple (tuple): Ordered, immutable collections of items.


# Tuple data
point = (4, 5)
print(point)  # Output: (4, 5)

Mapping Type

Dictionary (dict): Unordered, mutable collections of key-value pairs.


# Dictionary data
person = {"name": "Alice", "age": 25}
person["age"] = 26
print(person)  # Output: {'name': 'Alice', 'age': 26}

Set (set): Unordered collections of unique items.


# Set data
colors = {"red", "green", "blue"}
colors.add("yellow")
print(colors)  # Output: {'yellow', 'blue', 'green', 'red'}

Boolean Type

Boolean (bool): Represents True or False values.


is_open = True
is_closed = False
print(is_open)  # Output: True
print(is_closed)  # Output: False

None Type

NoneType: Represents the absence of a value.


# NoneType data
nothing = None
print(nothing)  # Output: None
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