C# Program to Count Vowels and Consonants

Use a C# program that loops through each character of a string, checks if it is a vowel with "aeiou".Contains(char.ToLower(c)), counts vowels and consonants separately, and prints the totals.

Examples

Inputhello

OutputVowels: 2, Consonants: 3

InputProgramming

OutputVowels: 3, Consonants: 8

Input123!@#

OutputVowels: 0, Consonants: 0

How to Think About It

To count vowels and consonants, read each character in the input string. Convert it to lowercase to simplify checks. If the character is a letter, check if it is one of the vowels (a, e, i, o, u). If yes, increase the vowel count; if not, increase the consonant count. Ignore non-letter characters.

Algorithm

1

Get input string from the user.

2

Initialize vowel and consonant counters to zero.

3

For each character in the string:

4

Check if it is a letter.

5

If it is a vowel, increment vowel count; else increment consonant count.

6

Print the counts of vowels and consonants.

Code

csharp

using System;
class Program {
    static void Main() {
        Console.Write("Enter a string: ");
        string input = Console.ReadLine();
        int vowels = 0, consonants = 0;
        foreach (char c in input) {
            if (char.IsLetter(c)) {
                char lower = char.ToLower(c);
                if ("aeiou".Contains(lower)) vowels++;
                else consonants++;
            }
        }
        Console.WriteLine($"Vowels: {vowels}, Consonants: {consonants}");
    }
}

Output

Enter a string: Programming
Vowels: 3, Consonants: 8

Dry Run

Let's trace the input "hello" through the code

1

Input received

input = "hello"

2

Initialize counters

vowels = 0, consonants = 0

3

Check each character

h (letter, not vowel) -> consonants = 1 e (vowel) -> vowels = 1 l (consonant) -> consonants = 2 l (consonant) -> consonants = 3 o (vowel) -> vowels = 2

4

Print result

Vowels: 2, Consonants: 3

Character	IsLetter	IsVowel	Vowels Count	Consonants Count
h	true	false	0	1
e	true	true	1	1
l	true	false	1	2
l	true	false	1	3
o	true	true	2	3

Why This Works

Step 1: Check if character is a letter

We use char.IsLetter(c) to ignore digits and symbols, counting only alphabetic characters.

Step 2: Convert to lowercase

Converting to lowercase with char.ToLower(c) simplifies vowel checking by avoiding case mismatches.

Step 3: Count vowels and consonants

If the character is in "aeiou", increment vowel count; otherwise, increment consonant count.

Alternative Approaches

Using LINQ to count vowels and consonants

csharp

using System;
using System.Linq;
class Program {
    static void Main() {
        Console.Write("Enter a string: ");
        string input = Console.ReadLine();
        int vowels = input.Count(c => "aeiouAEIOU".Contains(c));
        int consonants = input.Count(c => char.IsLetter(c) && !"aeiouAEIOU".Contains(c));
        Console.WriteLine($"Vowels: {vowels}, Consonants: {consonants}");
    }
}

This approach is concise and uses LINQ but may be less clear for beginners.

Using switch statement for vowel checking

csharp

using System;
class Program {
    static void Main() {
        Console.Write("Enter a string: ");
        string input = Console.ReadLine();
        int vowels = 0, consonants = 0;
        foreach (char c in input) {
            if (char.IsLetter(c)) {
                switch (char.ToLower(c)) {
                    case 'a': case 'e': case 'i': case 'o': case 'u': vowels++; break;
                    default: consonants++; break;
                }
            }
        }
        Console.WriteLine($"Vowels: {vowels}, Consonants: {consonants}");
    }
}

Using switch can be clearer for some learners but is more verbose.

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

Time Complexity

The program loops through each character once, so time grows linearly with input size.

Space Complexity

Only a few counters are used, so extra space is constant regardless of input size.

Which Approach is Fastest?

The basic loop is efficient and clear; LINQ is concise but may have slight overhead.

Approach	Time	Space	Best For
Basic loop with Contains	O(n)	O(1)	Clarity and beginner-friendly
LINQ Count with lambda	O(n)	O(1)	Concise code, intermediate users
Switch statement	O(n)	O(1)	Explicit vowel checks, readability