0002-datatypes-in-python.md

Python Data Types

Overview

In Python, data types define the kind of value a variable holds and what operations can be performed on it.
Python is a dynamically typed language, which means you don’t need to explicitly declare variable types — they are determined automatically at runtime.

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Basic Built-in Data Types

Data Type	Example Values	Description
int	6, 9, -9, 0	Represents whole (integer) numbers, positive or negative, without decimals.
float	2.3, 4.5, 0.5, -9.8	Represents real numbers (decimal values).
str	"hello world", "23r08sdh9d"	Represents a sequence of characters (text). Strings are enclosed in quotes.
bool	True, False	Represents Boolean values — either True or False.
NoneType	None	Represents the absence of a value or a null object.

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Example: Basic Data Types

# Integer
a = 6
b = -9

# Float
pi = 3.14
temperature = 36.6

# String
message = "Hello World"
code = "23r08sdh9d"

# Boolean
is_active = True
is_logged_in = False

# NoneType
result = None

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Printing in Python

To display output in Python, we use the print() function.

print("Hello World!")

Output:

Hello World!

You can print multiple values as well:

x = 10
y = 5
print("Sum:", x + y)

Output:

Sum: 15

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The type() Function

The type() function in Python returns the data type of a given object.

Syntax

type(object)

Example

print(type("True"))      # String
print(type("Hello"))     # String
print(type(2))           # Integer
print(type(2.3))         # Float
print(type(None))        # NoneType
print(type(True))        # Boolean

Output

<class 'str'>
<class 'str'>
<class 'int'>
<class 'float'>
<class 'NoneType'>
<class 'bool'>

Note: The output format <class 'typename'> shows that in Python, everything is an object of a specific class.

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Type Conversion

Python allows you to convert between data types using built-in functions such as int(), float(), and str().

num = "10"

print(int(num))      # Converts string to integer → 10
print(float(num))    # Converts string to float → 10.0
print(str(20))       # Converts integer to string → "20"

Output:

10
10.0
20

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Key Takeaways

• Python automatically infers the type of a variable at runtime.
• Use type() to check what data type a value or variable has.
• Convert between data types using casting functions like int(), float(), and str().
• None represents the absence of a value — it’s not the same as 0 or False.

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Practice Exercises

1. Create variables of each type (int, float, str, bool, None) and print their types.
2. Convert a string "100" into both an integer and a float.
3. Create a Boolean variable and print its type using the type() function.
4. Experiment with None — assign it to a variable and print its type.