Introduction

In Python, data types classify the kind of value that a variable can hold. Understanding data types is fundamental to writing effective and error-free code. Variables are used to store these values in memory, allowing us to refer to and manipulate them throughout our program.

Fundamental Data Types

Python has several built-in data types. We'll focus on the most common ones:

1. Integers (int)

Integers represent whole numbers (without a fractional part). They can be positive, negative, or zero.

# Example: Integer
age = 30
temperature = -5
count = 0

print(type(age))  # Output: <class 'int'> 

2. Floats (float)

Floats represent numbers with a decimal point (i.e., floating-point numbers). They are used for representing real numbers.

# Example: Float
price = 99.99
pi = 3.14159
distance = 123.45

print(type(price)) # Output: <class 'float'> 

3. Strings (str)

Strings represent sequences of characters. They are used to store text. Strings are enclosed in single quotes (') or double quotes (").

# Example: String
name = "Alice"
message = 'Hello, World!'
empty_string = ""

print(type(name)) # Output: <class 'str'> 

4. Booleans (bool)

Booleans represent truth values: True or False. They are often used in conditional statements and logical operations.

# Example: Boolean
is_active = True
is_valid = False

print(type(is_active)) # Output: <class 'bool'> 

Declaring and Using Variables

In Python, you don't need to explicitly declare the data type of a variable. You simply assign a value to a variable name, and Python automatically infers the type.

# Assigning values to variables
x = 10          # Integer
y = 2.5         # Float
name = "Bob"    # String
is_adult = True # Boolean

# Printing the values of variables
print(x)
print(y)
print(name)
print(is_adult)

# Performing operations with variables
sum_result = x + y
print("Sum:", sum_result)

greeting = "Hello, " + name + "!"
print(greeting) 

Important Note: Variable names are case-sensitive. myVar is different from myvar.

Type Conversion (Casting)

Sometimes you need to convert a value from one data type to another. Python provides built-in functions for type conversion:

• int(): Converts a value to an integer.
• float(): Converts a value to a float.
• str(): Converts a value to a string.
• bool(): Converts a value to a boolean.

# Type Conversion Examples
num_str = "10"
num_int = int(num_str)  # Convert string to integer
print(num_int + 5)     # Output: 15

num_float = float("3.14") #Convert String to Float
print(num_float * 2) #Output: 6.28

num = 5
num_str = str(num)  # Convert integer to string
print("The number is: " + num_str)

value = 0
boolean_value = bool(value)  #Convert to boolean - 0 evaluates to False
print(boolean_value)
value = 1
boolean_value = bool(value) #Convert to boolean - non-zero evaluates to True
print(boolean_value) 

Be careful when converting between data types, as invalid conversions can raise errors (e.g., trying to convert the string "abc" to an integer).