Python Basics

Data Types: Data types are classifications that specify the type of value a variable can hold and how that value can be used in a program. They inform the Python interpreter about the kind of operations that can be performed on the data, the range of possible values, and how much memory is required to store the data.

Built-in Data Types

Python provides several built-in data types that are categorized into Scalar Data Types and Aggregated Data Types. These data types define the nature of the data and how it can be processed in a program.

Scalar Data Types:

• int – Integer numbers
• float – Floating-point numbers
• bool – Boolean values (True or False)
• str – Strings (text)

Aggregated Data Types:

: Aggregated data types—also referred to as (built-in) data structures—are covered in the Data Structures (Buitl-in) topic.

• list – Ordered, mutable sequence
• tuple – Ordered, immutable sequence
• set – Unordered collection of unique items
• dict – Key-value pairs

Scalar Data Types

Scalar data types represent single, indivisible values. These are the basic building blocks for handling data in Python.

i). int

Used to store whole numbers, positive or negative, without decimals.

## Integer datatype Example
x = 10
y = -5
print(type(x))  # Output: <class 'int'>

ii) float – Floating-Point Numbers

Used to represent real numbers (i.e., numbers with decimal points).

##floating point datatype example
pi = 3.14159
temperature = -273.15
print(type(pi))  # Output: <class 'float'>

iii) bool – Boolean Values

Represents logical values: True or False. Commonly used in conditional statements.

## boolean datatype
is_python_fun = True
is_sky_green = False
print(type(is_python_fun))  # Output: <class 'bool'>

iv) str – String (Text)

Used to store sequences of characters, enclosed in either single ' ' or double quotes " ".

## string datatype example
message = "Hello, Python!"
print(type(message))  # Output: <class 'str'>

x = 42
print(type(x))  # Output: <class 'int'>

Typecasting in Python

Typecasting refers to converting a value from one data type to another. This is useful when you need to perform operations that require a specific data type, such as arithmetic operations on numbers stored as strings.

Python provides built-in functions like int(), float(), str(), and list() for typecasting.

(i) Typecasting with Scalar Data

## Typecasting with Scalar Data example
a = "100"
b = int(a)
print(b + 50)  
# Output: 150

(ii) Typecasting with Aggregate Data

## Typecasting with aggregate data example:
str_list = ["1", "2", "3"]
int_list = list(map(int, str_list))
print(int_list) 
# Output: [1, 2, 3]

Practice Examples

1. int (Integer)

a = 42
b = -5
c = a + b
print("Sum:", c)

2. float (Floating-point)

x = 3.14
y = 2.0
z = x * y
print("Product:", z)

3. bool (Boolean)

is_raining = True
has_umbrella = False
print("Can go out?", is_raining and has_umbrella)

4. str (String)

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

Practice Task:

# int – Multiply two integers
a = 6
b = 7
product = a * b
print("Product:", product)  # Output: Product: 42

# float – Divide and round
value = 7.5
divisor = 2
result = round(value / divisor, 2)
print("Result:", result)  # Output: Result: 3.75

# bool – Determine movie eligibility
has_ticket = True
is_seat_available = False
can_watch_movie = has_ticket and is_seat_available
print("Can watch movie?", can_watch_movie)  # Output: False

# str – Convert to uppercase and find length
word = "python"
uppercase_word = word.upper()
length = len(uppercase_word)
print("Uppercase:", uppercase_word)        # Output: PYTHON
print("Length:", length)                   # Output: 6

Operators in Python

Operators are special symbols or keywords in Python that are used to perform operations on variables and values. Python supports several categories of operators including:

• Arithmetic Operators – for basic math operations
• Comparison Operators – for comparing values
• Logical Operators – for combining conditional statements

➕ Arithmetic Operators

Used to perform mathematical operations.

a = 10
b = 3

print(a + b)   # 13
print(a - b)   # 7
print(a * b)   # 30
print(a / b)   # 3.333...
print(a // b)  # 3
print(a % b)   # 1
print(a ** b)  # 1000

Comparison Operators

x = 7
y = 10

print(x == y)   # False
print(x != y)   # True
print(x > y)    # False
print(x < y)    # True
print(x >= 7)   # True
print(y <= 10)  # True

if x = 10:  # SyntaxError! Use == for comparison

🧠 Logical Operators

a = 5
b = 10
c = 15

print(a < b and b < c)   # True
print(a > b or b < c)    # True
print(not a > b)         # True

💡 Practice Examples

# 1. Check if a number is positive and even
num = 8
if num > 0 and num % 2 == 0:
    print("Positive and Even")

# 2. Validate user login
username = "admin"
password = "1234"

if username == "admin" and password == "1234":
    print("Access Granted")
else:
    print("Access Denied")

# 3. Apply discount if purchase is over $100 or customer has a coupon
total = 120
has_coupon = False

if total > 100 or has_coupon:
    print("Discount Applied")
else:
    print("No Discount")

⚠️ Common Mistakes Summary