OOPS & Python Programming (4351108) - Summer 2025 Solution

Solution guide for OOPS & Python Programming (4351108) Summer 2025 exam

May 14, 2025

study-material solutions python 4351108 2025 summer

Question 1(a) [3 marks]

What is the purpose of a for loop in Python? Write an example.

Answer: A for loop is used to iterate over a sequence (like list, tuple, string) or other iterable objects and execute a block of code for each item in the sequence.

Code Example:

Python

Iteration: Automatically repeats code for each item
Simplicity: Cleaner than using while loops with counters

Mnemonic: "For Each Item Do"

Question 1(b) [4 marks]

List out rules for defining variables in python and list out data types in python.

Answer:

Rules for defining variables:

Rule	Example	Invalid Example
Must start with letter or underscore	`name = "John"`	`1name = "John"`
Can contain letters, numbers, underscores	`user_1 = "Alice"`	`user-1 = "Alice"`
Case-sensitive	`age` and `Age` are different
Cannot use reserved keywords	`count = 5`	`if = 5`

Python Data Types:

Data Type	Description	Example
int	Integer numbers	`x = 10`
float	Decimal numbers	`y = 10.5`
str	Text strings	`name = "John"`
bool	Boolean values	`is_active = True`
list	Ordered, changeable collection	`fruits = ["apple", "banana"]`
tuple	Ordered, unchangeable collection	`coordinates = (10, 20)`
dict	Key-value pairs	`person = {"name": "John", "age": 30}`
set	Unordered collection of unique items	`numbers = {1, 2, 3}`

Variable rules: Make them descriptive and meaningful
Data types: Python automatically determines the type

Mnemonic: "SILB-DTS" (String, Integer, List, Boolean, Dictionary, Tuple, Set)

Question 1(c) [7 marks]

Create a program to print prime numbers between 1 to N.

Answer:

Python

Algorithm Diagram:

Time complexity: O(N√N) - Optimized with square root approach
Space complexity: O(1) - Only uses constant space

Mnemonic: "Divide To Decide Prime"

Question 1(c) OR [7 marks]

Explain working of break, continue and pass statement in Python with examples.

Answer:

Statement	Purpose	Example
break	Terminates the loop completely	Stop loop when condition met
continue	Skips current iteration, continues with next	Skip specific items
pass	Null operation, does nothing	Placeholder for future code

1. break statement:

Python

2. continue statement:

Python

3. pass statement:

Python

Flow Control Diagram:

break: Exits completely from the loop
continue: Jumps to the next iteration
pass: Does nothing, placeholder for future code

Mnemonic: "BCP - Break Completely, Continue Partially, Pass silently"

Question 2(a) [3 marks]

Create a program that asks the user for a year and prints out whether it is a leap year or not.

Answer:

Python

Decision Tree:

Rule 1: Divisible by 4, not by 100
Rule 2: Or divisible by 400

Mnemonic: "4 Yes, 100 No, 400 Yes"

Question 2(b) [4 marks]

What are the key differences between a list and a tuple in Python?

Answer:

Feature	List	Tuple
Syntax	Created using `[]`	Created using `()`
Mutability	Mutable (can be changed)	Immutable (cannot be changed)
Methods	Many methods (append, remove, etc.)	Limited methods (count, index)
Performance	Slower	Faster
Use Case	When modification needed	When data shouldn't change
Memory	Uses more memory	Uses less memory

Comparison Diagram:

Lists: When you need to modify the collection
Tuples: When you need immutable data (faster, safer)

Mnemonic: "LIST - Lets Items Stay Transformable, TUPLE - Totally Unchangeable Permanent List Elements"

Question 2(c) [7 marks]

Create a program to find the sum of all the positive numbers entered by the user. As soon as the user enters a negative number, stop taking in any further input from the user and display the sum.

Answer:

Python

Process Flow:

Loop control: Terminates on negative input
Accumulator: Adds each positive number to running total

Mnemonic: "Sum Till Negative"

Question 2(a) OR [3 marks]

Create a program to find a maximum number among the given three numbers.

Answer:

Python

Comparison Logic:

Comparison: Uses logical operators to find maximum
Alternative: Built-in max() function for simplicity

Mnemonic: "Compare Each, Take Largest"

Question 2(b) OR [4 marks]

Given the str="abcdefghijklmnopqrstuvwxyz". Write a python program to extract every second character from above string.

Answer:

Python

String Slicing Diagram:

+---+---+---+---+---+---+---+---+---+---+---+
| a | b | c | d | e | f | g | h | i | j | k |...
+---+---+---+---+---+---+---+---+---+---+---+
  ^       ^       ^       ^       ^
  |       |       |       |       |
  0       2       4       6       8   (indices)

String slicing: [start:end:step] syntax
Step value: 2 selects every second character

Mnemonic: "Slice Step Selector"

Question 2(c) OR [7 marks]

Write a Python program to create a dictionary that stores student names and their marks. Display the names of students who have scored more than 75 marks.

Answer:

Python

Process Diagram:

Dictionary: Key-value pairs of student names and marks
Conditional filtering: Selects high scorers (>75)

Mnemonic: "Store All, Filter Some"

Question 3(a) [3 marks]

Write a program to find the length of a string excluding spaces.

Answer:

Python

String Processing:

"Hello World" → "HelloWorld" → Length: 10

Space removal: Using replace() or filtering
String length: Calculated after space removal

Mnemonic: "Count Characters, Skip Spaces"

Question 3(b) [4 marks]

List the dictionary methods in python and explain each with suitable examples.

Answer:

Method	Description	Example
`clear()`	Removes all items	`dict.clear()`
`copy()`	Returns a shallow copy	`new_dict = dict.copy()`
`get()`	Returns value for key	`value = dict.get('key', default)`
`items()`	Returns key-value pairs	`for k, v in dict.items():`
`keys()`	Returns all keys	`for k in dict.keys():`
`values()`	Returns all values	`for v in dict.values():`
`pop()`	Removes item with key	`value = dict.pop('key')`
`update()`	Updates dictionary	`dict.update({'key': value})`

Code Example:

Python

Access methods: get(), keys(), values(), items()
Modification methods: update(), pop(), clear()

Mnemonic: "GCUP-KPIV" (Get-Copy-Update-Pop, Keys-Pop-Items-Values)

Question 3(c) [7 marks]

Explain Python's List data type in detail.

Answer:

Python List: An ordered, mutable collection that can store items of different data types.

Feature	Description	Example
Creation	Using square brackets	`my_list = [1, 'hello', True]`
Indexing	Zero-based, negative indices	`my_list[0]`, `my_list[-1]`
Slicing	Extract parts	`my_list[1:3]`
Mutability	Can be modified	`my_list[0] = 10`
Methods	Many built-in methods	`append()`, `insert()`, `remove()`
Nesting	Lists within lists	`nested = [[1, 2], [3, 4]]`

Common List Methods:

Method	Purpose	Example
`append()`	Add item to end	`my_list.append(5)`
`insert()`	Add at position	`my_list.insert(1, 'new')`
`remove()`	Remove by value	`my_list.remove('hello')`
`pop()`	Remove by index	`my_list.pop(2)`
`sort()`	Sort list	`my_list.sort()`
`reverse()`	Reverse order	`my_list.reverse()`

List Operations Diagram:

Versatility: Stores different data types in one collection
Dynamic sizing: Grows or shrinks as needed

Mnemonic: "CAMP-IS" (Create, Access, Modify, Process, Index, Slice)

Question 3(a) OR [3 marks]

Write a program to input a string from the user and print it in the reverse order without creating a new string.

Answer:

Python

String Reversing Visualization:

"Hello" → "olleH"

Indices:  0   1   2   3   4
String:   H   e   l   l   o
Reversed: o   l   l   e   H
Indices: -1  -2  -3  -4  -5

Slicing with negative step: Reverses without new string
Efficient: No extra memory used for new string

Mnemonic: "Slice Backwards"

Question 3(b) OR [4 marks]

List the dictionary operations in python and explain each with suitable examples.

Answer:

Operation	Description	Example
Creation	Create a new dictionary	`d = {'key': 'value'}`
Access	Access by key	`value = d['key']`
Assignment	Add or update items	`d['new_key'] = 'new_value'`
Deletion	Remove items	`del d['key']`
Membership	Check if key exists	`if 'key' in d:`
Length	Count items	`len(d)`
Iteration	Loop through items	`for key in d:`
Comprehension	Create new dict	`{x: x**2 for x in range(5)}`

Code Example:

Python

Key-based access: Fast lookup by keys
Dynamic structure: Add/remove items as needed

Mnemonic: "CADMIL" (Create, Access, Delete, Modify, Iterate, Length)

Question 3(c) OR [7 marks]

Explain Python's set data type in detail.

Answer:

Python Set: An unordered collection of unique, immutable items.

Feature	Description	Example
Creation	Using curly braces or set()	`my_set = {1, 2, 3}` or `set([1, 2, 3])`
Uniqueness	No duplicates allowed	`{1, 2, 2, 3}` becomes `{1, 2, 3}`
Unordered	No indexing	Cannot use `my_set[0]`
Mutability	Set itself is mutable, but elements must be immutable	Can add/remove items
Math Operations	Set theory operations	union, intersection, difference
Use Cases	Remove duplicates, membership testing	Fast lookups

Common Set Operations:

Operation	Operator	Method	Description
Union	`\|`	`union()`	All elements from both sets
Intersection	`&`	`intersection()`	Common elements
Difference	`-`	`difference()`	Elements in first but not second
Symmetric Difference	`^`	`symmetric_difference()`	Elements in either but not both

Set Operations Diagram:

Fast membership: O(1) average time complexity
Mathematical operations: Set theory operations built-in

Mnemonic: "SUMO" (Sets are Unique, Mutable, and Ordered-less)

Question 4(a) [3 marks]

Explain statistics module with any three methods.

Answer:

The statistics module provides functions for calculating mathematical statistics of numeric data.

Method	Description	Example
`mean()`	Arithmetic average	`statistics.mean([1, 2, 3, 4, 5])` returns 3.0
`median()`	Middle value	`statistics.median([1, 3, 5, 7, 9])` returns 5
`mode()`	Most common value	`statistics.mode([1, 2, 2, 3, 4])` returns 2
`stdev()`	Standard deviation	`statistics.stdev([1, 2, 3, 4, 5])` returns 1.58...

Code Example:

Python

Data analysis: Functions for statistical calculations
Built-in module: No external installation needed

Mnemonic: "MMM Stats" (Mean, Median, Mode Statistics)

Question 4(b) [4 marks]

Explain function of user define function and user defined module in Python.

Answer:

Feature	User-defined Function	User-defined Module
Definition	Block of reusable code	Python file with functions/classes
Purpose	Code organization and reuse	Organizing related code
Creation	Using `def` keyword	Creating .py file
Usage	Call by function name	Import using `import` statement
Scope	Local to function	Accessible after import
Benefits	Reduces redundancy	Promotes code organization

User-defined Function Example:

Python

User-defined Module Example:

Python

Module Organization:

Function benefits: Code reuse, modular design
Module benefits: Organized code, namespace separation

Mnemonic: "FIR-MID" (Functions for Internal Reuse, Modules for Inter-file Distribution)

Question 4(c) [7 marks]

Write a Python code using user defined function to find the factorial of a given number using recursion.

Answer:

Python

Recursive Function Visualization:

Base case: Stops recursion when n=0 or n=1
Recursive case: Breaks problem into smaller subproblems

Mnemonic: "Factorial = Number times (Number minus one)!"

Question 4(a) OR [3 marks]

Explain math module with any three methods.

Answer:

The math module provides access to mathematical functions defined by the C standard.

Method	Description	Example
`math.sqrt()`	Square root	`math.sqrt(16)` returns 4.0
`math.pow()`	Power function	`math.pow(2, 3)` returns 8.0
`math.floor()`	Round down	`math.floor(4.7)` returns 4
`math.ceil()`	Round up	`math.ceil(4.2)` returns 5
`math.sin()`	Sine function	`math.sin(math.pi/2)` returns 1.0

Code Example:

Python

Mathematical operations: Advanced math functions
Constants: Mathematical constants like pi and e

Mnemonic: "SPT Math" (Square root, Power, Trigonometry in Math module)

Question 4(b) OR [4 marks]

Explain the concepts of global and local variables in Python.

Answer:

Variable Type	Scope	Definition	Access
Local	Inside function	Defined within function	Only within the function
Global	Entire program	Defined outside functions	Anywhere in the program

Example:

Python

Variable Scope Diagram:

Global: Accessible everywhere but needs global keyword to modify
Local: Limited to function scope, freed after function execution

Mnemonic: "GLOBAL Goes Everywhere, LOCAL Lives in Functions"

Question 4(c) OR [7 marks]

Create code with user defined function to check if given string is palindrome or not.

Answer:

Python

Palindrome Testing Process:

String cleaning: Removes spaces, converts to lowercase
Comparison: Checks against reversed string
Example palindromes: "radar", "madam", "A man a plan a canal Panama"

Mnemonic: "Clean, Reverse, Compare"

Question 5(a) [3 marks]

Define class and object with example.

Answer:

Class: A blueprint for creating objects that defines attributes and methods.

Object: An instance of a class with specific attribute values.

Code Example:

Python

Class-Object Relationship:

Class: Template with attributes and methods
Object: Concrete instance with specific values

Mnemonic: "CAMBO" (Classes Are Molds, Build Objects)

Question 5(b) [4 marks]

Classify constructor. Explain any one in detail.

Answer:

Constructor Type	Description	When Used
Default constructor	Created by Python if none defined	Simple class creation
Parameterized constructor	Takes parameters to initialize	Customized object creation
Non-parameterized constructor	Takes no parameters	Basic initialization
Copy constructor	Creates object from existing object	Object duplication

Parameterized Constructor Example:

Python

Constructor Flow:

Purpose: Initialize object attributes
Self parameter: Reference to the instance being created
Automatic call: Called when object is created

Mnemonic: "PICAN" (Parameters Initialize Constructor And Name)

Question 5(c) [7 marks]

Develop and explain a python code to implement hierarchical inheritance.

Answer:

Python

Hierarchical Inheritance Diagram:

Base class: Common attributes/methods for all vehicles
Derived classes: Specialized behaviors for specific vehicle types
Method inheritance: Child classes inherit parent class methods

Mnemonic: "Parents Share, Children Specialize"

Question 5(a) OR [3 marks]

What is the init method in Python? Explain its purpose with a suitable example.

Answer:

The __init__ method is a special method (constructor) in Python classes that is automatically called when an object is created.

Purpose:

Initialize object attributes
Set up the initial state of the object
Execute code that must run when object is created

Example:

Python

Automatic execution: Called when object is created
Self parameter: References the current instance
Multiple parameters: Can accept any number of arguments

Mnemonic: "ASAP" (Attributes Set At Production)

Question 5(b) OR [4 marks]

Classify methods in Python class. Explain any one in detail.

Answer:

Method Type	Description	Definition
Instance Method	Operates on object instance	Regular method with `self`
Class Method	Operates on class itself	Decorated with `@classmethod`
Static Method	Doesn't need class or instance	Decorated with `@staticmethod`
Magic/Dunder Method	Special built-in methods	Surrounded by double underscores

Instance Method Example:

Python

Method Classification:

Instance methods: Access and modify object state
Self parameter: Reference to the instance
Object-specific: Results depend on the instance state

Mnemonic: "SIAM" (Self Is Always Mentioned in instance methods)

Question 5(c) OR [7 marks]

Develop a Python code for Polymorphism and explain it.

Answer:

Python

Polymorphism Diagram:

Method overriding: Subclasses implement their own versions
Single interface: Same method name for different behavior
Flexibility: Code works with any class in the hierarchy
Dynamic binding: Correct method called based on object type

Mnemonic: "Same Method, Different Behavior"