a) set() and setdefault() Methods in Dictionary
1. set() Function
In Python, set() is not a dictionary method but a built-in function used to create a set — an unordered collection of unique elements. It’s often used to eliminate duplicates from lists or other iterables.
Example:
numbers = [1, 2, 2, 3, 4, 4, 5]
unique_numbers = set(numbers)
print(unique_numbers)
Output: {1, 2, 3, 4, 5}
2. setdefault() Method (Dictionary Method)
The setdefault() method returns the value of a key if it is present in the dictionary. If not, it inserts the key with a specified default value.
Syntax: dictionary.setdefault(key, default_value)
- If the key exists: returns its value.
- If the key does not exist: inserts key with default_value and returns default_value.
Example:
student = {'name': 'Rahul', 'age': 21}
# Key exists
print(student.setdefault('name', 'Unknown'))
# Key does not exist, so it's added
print(student.setdefault('branch', 'CSE'))
print(student)Output:
b) Program to Swap the Case of a Given String
Problem Statement:
Write a Python program that takes a string input and returns a new string with all uppercase letters converted to lowercase and vice versa.
Program:
Example Output:
