Python Program to Check if Character is Vowel or Consonant

Use a Python program that takes a character input and checks if it is in 'aeiouAEIOU' to determine if it's a vowel; otherwise, it is a consonant, like if char.lower() in 'aeiou': print('Vowel') else: print('Consonant').

Examples

Inputa

OutputVowel

InputB

OutputConsonant

Inputz

OutputConsonant

How to Think About It

To check if a character is a vowel or consonant, first consider vowels as the letters a, e, i, o, u in both uppercase and lowercase. Then, compare the input character to this set. If it matches any vowel, it is a vowel; otherwise, it is a consonant.

Algorithm

1

Get a single character input from the user.

2

Convert the character to lowercase to handle uppercase inputs.

3

Check if the character is in the set of vowels 'aeiou'.

4

If yes, print 'Vowel'.

5

Otherwise, print 'Consonant'.

Code

python

char = input('Enter a single character: ')
if char.lower() in 'aeiou':
    print('Vowel')
else:
    print('Consonant')

Output

Enter a single character: a
Vowel

Dry Run

Let's trace the input 'B' through the code

1

Input character

User inputs 'B'

2

Convert to lowercase

'B'.lower() becomes 'b'

3

Check if vowel

'b' in 'aeiou' is False

4

Print result

Print 'Consonant'

Step	Character	Lowercase	Is Vowel?	Output
1	B	b	No	Consonant

Why This Works

Step 1: Convert to lowercase

Using char.lower() ensures the program treats uppercase and lowercase letters the same.

Step 2: Check membership

Checking if the character is in 'aeiou' quickly tells if it is a vowel.

Step 3: Print result

If the character is a vowel, print 'Vowel'; otherwise, print 'Consonant'.

Alternative Approaches

Using a set for vowels

python

char = input('Enter a character: ')
vowels = {'a', 'e', 'i', 'o', 'u'}
if char.lower() in vowels:
    print('Vowel')
else:
    print('Consonant')

Using a set can be faster for membership checks and is more readable.

Using if-elif for each vowel

python

char = input('Enter a character: ').lower()
if char == 'a' or char == 'e' or char == 'i' or char == 'o' or char == 'u':
    print('Vowel')
else:
    print('Consonant')

This method is longer and less efficient but explicit for beginners.

Complexity: O(1) time, O(1) space

Time Complexity

Checking if a character is in a fixed set of vowels takes constant time, O(1), because the set size is small and fixed.

Space Complexity

The program uses constant space, O(1), as it only stores a few variables and a small set of vowels.

Which Approach is Fastest?

Using a set for vowels is generally faster for membership checks than a string, but for such a small fixed set, the difference is negligible.

Approach	Time	Space	Best For
String membership check	O(1)	O(1)	Simple and readable code
Set membership check	O(1)	O(1)	Slightly faster membership, good for larger sets
If-elif chain	O(1)	O(1)	Explicit but verbose, good for beginners