How to Count Number of Vowels in a String Using Sets in Python

Submitted by razormist on Sunday, November 9, 2025 - 23:51.

In this tutorial, we will learn how to program "How to Count the Number of Vowels in a String Using Sets in Python". The objective is to count the vowels in a given string using sets. This tutorial will guide you step by step through the process of identifying and counting vowels. By the end of this tutorial, you will have a solid understanding of how to implement this task effectively in Python, helping you strengthen your problem-solving skills and improve your coding abilities.

This topic is straightforward and easy to understand. Simply follow the instructions provided, and you’ll complete it with ease. The program will guide you step by step through the process of counting vowels using sets. So, let’s dive into the coding process!

Getting Started:

First you will have to download & install the Python IDLE's, here's the link for the Integrated Development And Learning Environment for Python https://www.python.org/downloads/.

Creating Main Function

This is the main function of the application. The following code will display a simple GUI in terminal console that will display program. To do this, simply copy and paste these blocks of code into the IDLE text editor.

while True:
    print("\n============== Count Number of Vowels in a String Using Sets ==============\n")
 
    s = input("Enter string: ")
    count = 0
    vowels = set("aeiouAEIOU")  # include uppercase vowels
    for letter in s:
        if letter in vowels:
            count += 1
 
    print("Count of vowels is:", count)
 
    # Ask user if they want to try again
    opt = input("\nDo you want to try again? (yes/no): ").strip().lower()
    if opt == 'no':
        print("Exiting program...")
        break
    elif opt != 'yes':
        print("Invalid choice. Exiting program...")
        break

This Python program counts the number of vowels in a user-provided string using a set for fast membership checking. It considers both uppercase and lowercase vowels (`A, E, I, O, U, a, e, i, o, u`). The program iterates through each character of the string, increments a counter when a vowel is found, and displays the total count. It repeats the process until the user chooses to exit.

Output:

There you have it we successfully created How to Count Number of Vowels in a String Using Sets in Python. I hope that this simple tutorial help you to what you are looking for. For more updates and tutorials just kindly visit this site. Enjoy Coding!

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