Ruby Program to Check Vowel or Consonant

Use if 'aeiouAEIOU'.include?(char) to check if a character is a vowel; otherwise, it is a consonant in Ruby.

Examples

Inputa

Outputa is a vowel

Inputz

Outputz is a consonant

InputE

OutputE is a vowel

How to Think About It

To check if a letter is a vowel or consonant, first get the character input. Then see if it is one of the vowels (a, e, i, o, u) ignoring case. If yes, say it is a vowel; if not, say it is a consonant.

Algorithm

1

Get a single character input from the user

2

Convert the character to lowercase or check both cases

3

Check if the character is in the set of vowels (a, e, i, o, u)

4

If yes, print that it is a vowel

5

Otherwise, print that it is a consonant

Code

ruby

print 'Enter a character: '
char = gets.chomp
if 'aeiouAEIOU'.include?(char)
  puts "#{char} is a vowel"
else
  puts "#{char} is a consonant"
end

Output

Enter a character: a
a is a vowel

Dry Run

Let's trace input 'a' through the code

1

Input character

User enters 'a'

2

Check vowel

'aeiouAEIOU'.include?('a') returns true

3

Print result

Print 'a is a vowel'

Step	Character	Is Vowel?
1	a	true

Why This Works

Step 1: Check membership

The include? method checks if the input character is inside the string of vowels.

Step 2: Case sensitivity

We include both uppercase and lowercase vowels to handle any case input.

Step 3: Output result

If the character is a vowel, print it as vowel; otherwise, print as consonant.

Alternative Approaches

Using a lowercase conversion

ruby

print 'Enter a character: '
char = gets.chomp.downcase
if 'aeiou'.include?(char)
  puts "#{char} is a vowel"
else
  puts "#{char} is a consonant"
end

Converts input to lowercase first, so only lowercase vowels need to be checked.

Using a case statement

ruby

print 'Enter a character: '
char = gets.chomp
case char.downcase
when 'a', 'e', 'i', 'o', 'u'
  puts "#{char} is a vowel"
else
  puts "#{char} is a consonant"
end

Uses Ruby's case statement for clearer multiple condition checks.

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

Time Complexity

Checking if a character is in a fixed string of vowels is a constant time operation.

Space Complexity

Only a few variables and a fixed string are used, so space is constant.

Which Approach is Fastest?

All approaches run in constant time; using include? or case is equally efficient.

Approach	Time	Space	Best For
Using include? with both cases	O(1)	O(1)	Simple and direct check
Using lowercase conversion	O(1)	O(1)	Cleaner code, fewer vowels to check
Using case statement	O(1)	O(1)	Clear multiple condition handling