2.3 Common Data Types in Python: Strings, Integers, Floats, and Booleans

Introduction

Python supports several data types to store different kinds of information. Understanding these data types is essential because they determine how data is stored, manipulated, and used in your programs. In this sub-section, you’ll learn about four of the most common data types in Python:

In Python, different types of data are used to store and manipulate values. The four most commonly used data types are:

• Strings (str) – Used for text
• Integers (int) – Used for whole numbers
• Floats (float) – Used for decimal numbers
• Booleans (bool) – Used for True/False values

Understanding these data types is essential for performing operations, making comparisons, and writing efficient Python programs.

2.3.1 Strings (str)

A string in Python is a sequence of characters enclosed in single quotes ('), double quotes ("), or triple quotes (''' or """). Strings are used to store textual data, such as names, messages, or any sequence of characters.

Creating Strings

text1 = "Hello, Python!"  # Using double quotes
text2 = 'Python is fun!'  # Using single quotes
text3 = """This is a 
multi-line string."""  # Using triple quotes

Accessing Characters in a String

You can access individual characters in a string using indexing. Python uses zero-based indexing, meaning the first character is at index 0.

message = "Python"
print(message[0])  # Output: P
print(message[3])  # Output: h

String Operations

# Concatenation (joining strings)
first_name = "John"
last_name = "Doe"
full_name = first_name + " " + last_name
print(full_name)  # Output: John Doe

# Repeating a string
repeat_text = "Hello " * 3
print(repeat_text)  # Output: Hello Hello Hello

# String length
print(len(full_name))  # Output: 8

2.3.2 Integers (int)

An integer is a whole number, meaning it has no decimal point. It can be positive, negative, or zero.

Creating Integers

num1 = 10  # Positive integer
num2 = -5  # Negative integer
num3 = 0   # Zero

Basic Operations with Integers

a = 15
b = 4

print(a + b)  # Addition: Output: 19
print(a - b)  # Subtraction: Output: 11
print(a * b)  # Multiplication: Output: 60
print(a // b)  # Floor division: Output: 3
print(a % b)  # Modulus (remainder): Output: 3
print(a ** b)  # Exponentiation: Output: 50625

Using Integers in Comparisons

x = 10
y = 20

print(x < y)  # Output: True
print(x == y)  # Output: False

2.3.3 Floats (float)

A float (floating-point number) is a number that contains a decimal point. Floats are used for representing real numbers, such as measurements and calculations requiring precision.

Creating Floats

pi = 3.14159  # A floating-point number
temperature = -12.5  # A negative float

Basic Operations with Floats

Floats can be used in mathematical operations just like integers.

num1 = 7.5
num2 = 2.5

print(num1 + num2)  # Output: 10.0
print(num1 - num2)  # Output: 5.0
print(num1 * num2)  # Output: 18.75
print(num1 / num2)  # Output: 3.0

Using Floats in Comparisons

a = 10.5
b = 10

print(a > b)  # Output: True
print(a == b)  # Output: False

Converting Between Integers and Floats

You can convert an integer to a float and vice versa using float() and int() functions.

x = 10
y = 3.7

x_float = float(x)  # Convert int to float
y_int = int(y)  # Convert float to int

print(x_float)  # Output: 10.0
print(y_int)  # Output: 3

2.3.4 Booleans (bool)

A boolean (bool) represents one of two values: True or False. Booleans are often used in conditional statements and logical operations.

Creating Boolean Variables

is_sunny = True
is_raining = False

Boolean Expressions

Boolean values result from comparison operations.

a = 10
b = 20

print(a > b)  # Output: False
print(a < b)  # Output: True
print(a == 10)  # Output: True

Boolean Values of Different Data Types

Python considers some values truthy (evaluates to True) and some values falsy (evaluates to False).

print(bool(0))  # Output: False
print(bool(1))  # Output: True
print(bool(""))  # Output: False (empty string)
print(bool("Hello"))  # Output: True (non-empty string)
print(bool([]))  # Output: False (empty list)
print(bool([1, 2, 3]))  # Output: True (non-empty list)

2.3.5 Summary

The following concepts were discussed in this section:

• Strings (str) are used to store text and are enclosed in quotes. They support operations like concatenation and repetition.
• Integers (int) represent whole numbers and support basic arithmetic operations.
• Floats (float) represent decimal numbers and are used in calculations requiring precision.
• Booleans (bool) store True or False values and are used in logical conditions.

Understanding these data types is essential for writing effective Python programs.

What’s Next?

In the next lesson, 2.4 Type Conversion (e.g., from String to Integer), we will explore how to convert data between different types to perform calculations and handle user input correctly.