3.1 Introduction to Python Programming Listen

Python is a high-level, widely-used programming language famous for its simplicity and readability. It is versatile and is used worldwide in fields like web development, data analysis, and artificial intelligence (AI).

3.1.1 Basic Programming Concepts

Computer programming is the process of creating a set of instructions that tell a computer how to perform a task. The programming lifecycle consists of four steps:

1. Write Code: Type the instructions in a code editor.
2. Compile / Interpret: The computer translates code into machine language (0s and 1s).
3. Execute: Run the program to produce the desired result.
4. Fix Errors (Debugging): Correct logic or syntax mistakes if results differ from expectation.

Setting Up the Python Development Environment

1. Download Python: Visit https://www.python.org, navigate to Downloads, and get the latest version (e.g., Python 3.13.x).
2. Install Python: Run the downloaded installer.
3. CRITICAL STEP: Check the box "Add Python to PATH" during setup so system command line can access Python.
4. Set up an IDE: Use PyCharm (Community Edition), VS Code, or IDLE (built into Python).
5. Configure IDE: Set interpreter path (e.g., C:\Python312\python.exe).
6. Test Setup: Create test.py and execute the test program below.

print("Hello, Python!")

Step-by-Step Screenshots (Tap any image to enlarge)

3.2 Basic Python Syntax & Structure Listen

The print() function is used to display output text on the screen. Notice how clean Python syntax is compared to older languages:

print("K2 is the second-highest mountain in the world")
print("Edhi Foundation operates the world's largest volunteer ambulance network.")

Python Comments

Comments are lines ignored by the interpreter. They explain code logic to programmers:

• Single-line comment: Starts with # symbol.
• Multi-line block: Enclosed in triple quotes ''' ... '''.

# This is a single line comment
print("K2 is the second-highest mountain in the world")

''' Multi-line comment block
    explaining information for students '''
print("Edhi Foundation operates the world's largest volunteer ambulance network.")

3.2.1 Variables in Python

A variable is a named storage container in memory holding values that can change during program execution.

print("Hello dear students!")

age = 71
print("Azam lived for", age, "years")

age = 60
print("Iqbal lived for", age, "years")

Variable Naming Rules

• Must begin with a letter (a-z, A-Z) or an underscore ( _ ).
• Remaining characters can be letters, digits (0-9), or underscores.
• Names are case-sensitive (e.g., age and Age are distinct).
• Python reserved keywords cannot be used as variable names.

Basic Data Types

Input and Output Operations

input(): Function displays prompt text and waits for user entry. Returns input as a string (str).

print(): Displays output value on console screen.

name = input("Enter your name: ")
print("Hello, " + name + "!")

Type Conversion with int() & float()

Convert string input into numbers using int() for whole numbers or float() for decimals.

user_age = int(input("Enter your age: "))
print("Your age is:", user_age)

user_height = float(input("Enter height in meters: "))
print("Your height is", user_height, "meters")

3.3 Operators & Expressions

Operators are symbols performing calculations on values (operands). Expressions combine variables, constants, and operators.

3.3.1 Arithmetic Operators

# Define variables
a = 10
b = 3

# Perform all arithmetic operations on these numeric variables and print results
print(a, "+", b, "=", a + b)     # Output: 10+3=13
print(a, "-", b, "=", a - b)     # Output: 10-3=7
print(a, "*", b, "=", a * b)     # Output: 10*3=30
print(a, "/", b, "=", a / b)     # Output: 10/3=3.3333333333333335
print(a, "//", b, "=", a // b)   # Output: 10//3=3   #floor division
print(a, "%", b, "=", a % b)     # Output: 10%3=1
print(a, "**", b, "=", a ** b)   # Output: 10**3=1000   # represent power operator:

3.3.2 Comparison Operators

# Define variables
x = 10
y = 5

# Greater than
print(x, ">", y, "=", x > y)      # Output: 10 > 5 = True
# Less than
print(x, "<", y, "=", x < y)      # Output: 10 < 5 = False
# Equal to
print(x, "==", y, "=", x == y)    # Output: 10 == 5 = False
# Not equal to
print(x, "!=", y, "=", x != y)    # Output: 10 != 5 = True
# Greater than or equal to
print(x, ">=", y, "=", x >= y)    # Output: 10 >= 5 = True
# Less than or equal to
print(x, "<=", y, "=", x <= y)    # Output: 10 <= 5 = False

3.3.3 Compound Assignment Operators

# Define initial values
a = 10
b = 5

# Assignment
a = a
print("a =", a)                          # Output: a = 10

# Addition assignment
a += b
print("a after addition =", a)           # Output: a = 15

# Subtraction assignment
a -= b
print("a after subtraction =", a)        # Output: a = 10

# Multiplication assignment
a *= b
print("a after multiplication =", a)     # Output: a = 50

# Division assignment
a /= b
print("a after division =", a)           # Output: a = 10.0

# Floor division assignment
a //= b
print("a after floor division =", a)     # Output: a = 2.0

# Modulus assignment
a %= b
print("a after modulus =", a)            # Output: a = 2.0

# Exponentiation assignment
a **= b
print("a after exponentiation =", a)     # Output: a = 32.0

3.3.4 Logical Operators

Logical operators are used to combine multiple conditions or expressions. The most common logical operators are and, or, and not — they perform logical operations and return Boolean values (True or False) based on the evaluation of the expressions involved.

# Define variables
x = True
y = False

# Logical AND
logical_and = x and y
print(x, "and", y, "=", logical_and)      # Output: True and False = False

# Logical OR
logical_or = x or y
print(x, "or", y, "=", logical_or)        # Output: True or False = True

# Logical NOT
logical_not_x = not x
print("not", x, "=", logical_not_x)       # Output: not True = False

logical_not_y = not y
print("not", y, "=", logical_not_y)       # Output: not False = True

3.3.5 Operator Precedence

Precedence rules determine evaluation order:

1. Parentheses ( ) — highest priority.
2. Exponentiation ** — right-associative power operator.
3. Multiplication / Division / Modulo (*, /, //, %).
4. Addition / Subtraction (+, -).

print(4 * 3 + 10 / 2 - 11 % 3)

Book full demonstration program: (note the f before each string — in Python, f-strings are used for string interpolation, embedding variables or expressions inside a string):

print("= PYTHON OPERATOR PRECEDENCE DEMONSTRATION =")

# 1. Arithmetic Operators
print("1. ARITHMETIC OPERATORS:")
print(f"3 + 2 * 5 = {3 + 2 * 5}")        # Multiplication before addition
print(f"(3 + 2) * 5 = {(3 + 2) * 5}")    # Parentheses change the order
print(f"3 ** 2 = {3 ** 2}")              # Exponentiation
print(f"2 ** 3 * 4 = {2 ** 3 * 4}")      # Exponentiation before multiplication
print(f"15 / 3 * 2 = {15 / 3 * 2}")      # Division and multiplication (left to right)
print(f"15 // 4 + 2 = {15 // 4 + 2}")    # Floor division before addition
print(f"11 // 4 + 2 = {11 // 4 + 2}")    # Floor division before addition
print(f"17 % 5 * 2 = {17 % 5 * 2}")      # Modulo before multiplication

Textbook Exam Practicals Solver

All four textbook exercise practicals are pre-loaded with interactive validation!

name = input("Enter your name: ")
print("Hello,", name, "! Welcome to Python programming.")

num1 = int(input("Enter first number: "))
num2 = int(input("Enter second number: "))

sum_val = num1 + num2
print("The sum is:", sum_val)

n1 = int(input("Enter number 1: "))
n2 = int(input("Enter number 2: "))
n3 = int(input("Enter number 3: "))
n4 = int(input("Enter number 4: "))
n5 = int(input("Enter number 5: "))

avg = (n1 + n2 + n3 + n4 + n5) / 5
print("The average is:", avg)

print("10 // 3 =", 10 // 3)
print("10 / 3 =", 10 / 3)
print("10 % 3 =", 10 % 3)
print("2 ** 4 =", 2 ** 4)

Gamified Practice Quiz

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Chapter Summary

• Python is high-level, readable, and used in AI, web development, and data science.
• Always select "Add Python to PATH" when installing from python.org.
• input() reads string inputs — use int() / float() to convert.
• Variable names are case-sensitive and cannot use reserved keywords (like if, else, for).
• Operators include arithmetic (+ - * / // % **), comparison (> < == != >= <=), and logical (and or not).
• Operator precedence order: Parentheses () > Power ** > Mult/Div * / // % > Add/Sub + -.

4.1 Decision Making Listen

Decision making in programming allows the program to choose different actions based on conditions. This is similar to how we make decisions in real life — for example, deciding whether to take an umbrella based on the weather situation. Python provides a variety of conditional statements to implement decision making.

4.1.1 if Statement

The if statement lets us make decisions based on conditions. If the condition is true, it runs a block of code.

# Syntax of if statement
# if condition:
#     code to run if the condition is true

temperature = 35
if temperature > 30:
    print("It's a hot day")

4.1.2 if-else Statement

The if-else statement allows us to execute one block of code if a condition is true and another block if the condition is false.

# Syntax of if-else statement
# if condition:
#     code to run if the condition is true
# else:
#     code to run if the condition is false

temperature = 15
if temperature > 30:
    print("It's a hot day")
else:
    print("It's not a hot day")

4.1.3 Nested Conditions

Sometimes, we need to check multiple conditions inside another condition. This is called nesting.

weather = "rainy"
temperature = 10

if weather == "rainy":
    if temperature < 15:
        print("Wear a raincoat")
    else:
        print("Take an umbrella")
else:
    print("Enjoy your day!")

Explanation: the code checks if the weather is rainy. If it is, it then checks if the temperature is below 15 degrees. If both conditions are true, it prints "Wear a raincoat". If the weather is rainy but the temperature is not below 15, it prints "Take an umbrella". If the weather is not rainy, it prints "Enjoy your day!"

4.2 Looping Constructs Listen

Loops help us repeat actions, making our code more efficient and easier to read. There are two main types of loops in Python: while loops and for loops.

4.2.1 while Loop

A while loop runs as long as a condition is true. It checks the condition before each iteration and stops running when the condition is no longer true.

# Syntax of while loop
# while condition:
#     code to run while the condition is true

number = 1
while number < 10:
    print(number)
    number += 1

Explanation: the loop prints the current value of the number and then adds 1 to it. This loop continues until the number reaches 10, at which point the loop stops running.

4.2.2 for Loop

A for loop repeats a block of code a specific number of times. It is commonly used to iterate over a sequence (like a list, tuple, or string).

# Syntax of for loop
# for variable in sequence:
#     code to run for each element in the sequence

friends = ["Sami", "Raza", "Moosa"]
for friend in friends:
    print("Welcome to:", friend)

4.2.3 range() Function

We can use the range() function to generate a sequence of numbers, which is often used in for loops.

for i in range(5):
    print(i)

End Statement (end parameter of print())

The end statement is not a separate command, but rather an optional parameter of the print() function. By default, every print() ends with a newline character, but you can change what gets printed at the end using the end parameter.

print("Azhar Shah", end=" ")
print("Ahsan")

print("Ayyan", end="***")
print("Naveed")

for i in range(1, 6):
    print(i, end=" ")

4.2.4 Nested Loops

Nested loops are loops inside other loops. For each iteration of the outer loop, the inner loop runs completely. We use nested loops when we need to perform repetitive tasks within tasks.

for i in range(3):          # Outer loop
    for j in range(4):      # Inner loop
        print(i, end=" ")
    print()                 # Separator after each outer loop

n = 5
for i in range(1, n + 1):
    for j in range(i):      # Inner loop runs 'i' times
        print("*", end="")
    print()                 # New line after each row

4.3 Libraries in Python Listen

Python offers an extensive standard library that includes built-in modules and data structures. In Python, libraries are like toolboxes full of useful tools that help you solve different problems without having to build everything from scratch.

random Library

import random

# Generate a random number between 1 to 10
number = random.randint(1, 10)
print("The random number is:", number)

(The value will be different every time the program runs — any number between 1 and 10.)

statistics Library

import statistics

# Calculate the mean of a list of numbers
data = [23, 45, 67, 89, 12, 44, 56]
mean_value = statistics.mean(data)
print("The mean value is:", mean_value)

Explanation: the statistics library is a great tool for performing basic statistical calculations, such as finding the mean, median, and mode of a set of data. This can be particularly useful in data analysis tasks.

4.4 Lists in Python Listen

In Python, a list is a versatile data structure that can hold a collection of items. You can create, access, and modify lists easily.

4.4.1 Creating Lists

A list is created by placing items inside square brackets [ ], separated by commas. Lists can contain items of different types, such as numbers, strings, or even other lists.

fruits = ["Mango", "Apple", "Banana"]
print(fruits)

4.4.2 Accessing List Items

You can access items in a list by referring to their index, starting from 0.

fruits = ["Mango", "Apple", "Banana"]
print(fruits[1])

4.4.3 Modifying a List

You can modify list items by accessing them via their index and assigning a new value.

fruits = ["Mango", "Apple", "Banana"]
fruits[0] = "Orange"
fruits.append("Pineapple")
print(fruits)

4.4.4 Operations on Lists

Python provides several built-in methods to work with lists. Here are a few useful ones:

students = ["Ahmed", "Sara", "Ali"]
students.append("Hina")
print(students)

students = ["Ali", "Hina", "Sara", "Sara"]
students.remove("Sara")
print(students)

Note: only the first matching item is removed.

numbers = [34, 12, 89, 5, 23]
numbers.sort()
print(numbers)

fruits = ["Apple", "Banana", "Orange", "Mango"]
fruits.reverse()
print(fruits)

4.5 Testing and Debugging in Python Listen

In Python programming, testing and debugging are essential practices to ensure that your code works correctly and efficiently.

4.5.1 Testing

Testing is the process of running your code with various inputs to check if it behaves as expected. The goal is to find and fix any issues before the code is used in real-world applications.

import unittest

def add(a, b):
    return a + b

class TestAdd(unittest.TestCase):
    def test_add(self):
        self.assertEqual(add(2, 3), 5)
        self.assertEqual(add(-1, 1), 0)

if __name__ == "__main__":
    unittest.main()

4.5.2 Debugging

Debugging is the process of finding and fixing errors (bugs) in your code. It involves identifying the root cause of problems and making the necessary changes.

• Print Statements: adding print statements to check the values of variables at different stages of the code.
• Debugging Tools: using tools like pdb (Python Debugger) to step through the code, inspect variables, and understand the flow of execution.
• Error Messages: reading and interpreting error messages to locate the source of the problem.

Textbook Exam Practicals Solver

All five textbook exercise practicals are pre-loaded with interactive validation!

for i in range(1, 21):
    if i % 2 != 0:
        print(i, end=" ")

import random
import statistics

numbers = []
for i in range(5):
    numbers.append(random.randint(1, 20))

print("The random numbers are:", numbers)
print("The mean is:", statistics.mean(numbers))

dishes = ["Biryani", "Nihari", "Karahi", "Seekh Kebabs"]

dishes.append("Quorma")
dishes[2] = "Chicken Karahi"
dishes.remove("Nihari")

print(dishes)

for i in range(3):          # 3 rows
    for j in range(5):      # 5 columns
        print("*", end="")
    print()

for i in range(1, 6):           # Outer: 1 to 5
    for j in range(1, 11):      # Inner: 1 to 10
        print(f"{i} x {j} = {i * j:2d}", end=" ")
    print()                     # New line after each table

Gamified Practice Quiz

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Chapter Summary

• Decision making: if, if-else, and nested if let the program choose actions based on conditions. Indentation defines the block/scope.
• while loop: repeats code as long as a condition is true (checks before each iteration).
• for loop: iterates over a sequence (list, tuple, string).
• range() function: range(stop), range(start, stop), range(start, stop, step).
• end parameter: print(..., end="") controls what is printed at the end instead of a newline.
• Nested loops: for each iteration of the outer loop, the inner loop runs completely (used for patterns).
• Libraries: random (randint), statistics (mean, median, mode) — import only what you need.
• Lists: create with [ ], access by index (starts at 0), modify by index, append(), remove(), sort(), reverse().
• Testing: unit, integration, functional, regression. Debugging: print statements, pdb, error messages.