Count the Number of Vowels in a String in C++

In this exercise, you will write a C++ function that counts how many vowels are present in a given string. Vowel detection is a common task in string manipulation, text analysis, and natural language processing.

The function should be able to handle both lowercase and uppercase vowels, and return the total count found. By completing this task, you'll reinforce your understanding of loops, conditionals, and string traversal in C++.

This is a beginner-friendly task that builds foundational logic used in more advanced textual data operations.

Implementation Details

1. Traversal

We use a range-based for loop to visit every character (char ch) in the string from beginning to end.

2. Normalization

Using tolower() allows us to check only for 'a, e, i, o, u' without needing to write separate logic for uppercase letters.

3. The Counter

A simple integer variable acts as an accumulator, incrementing by 1 every time the condition (is it a vowel?) is met.

Objective

1. Define a function that takes a string as a parameter.
2. Loop through each character of the string.
3. Check if the character is a vowel (a, e, i, o, u) regardless of case.
4. Return the total count and display it in the console.

Example C++ Exercise

vowel_counter.cpp Strings

#include <iostream>
#include <string>

using namespace std;

// Function to count the number of vowels in a string
int countVowels(string text) {
    int count = 0; // Initialize counter

    // Loop through each character in the string
    for (char ch : text) {
        // Convert to lowercase for easier comparison
        ch = tolower(ch);

        // Check if the character is a vowel
        if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u') {
            count++; // Increment if a vowel is found
        }
    }

    return count;
}

int main() {
    string input;

    // Prompt the user to enter a string
    cout << "Enter a string: ";
    getline(cin, input); // Read the full line (including spaces)

    // Call the function and display the result
    int vowels = countVowels(input);
    cout << "Number of vowels in the string: " << vowels << endl;

    return 0;
}

Example Output:

Enter a string: Hello World
Number of vowels in the string: 3

Objective

Example C++ Exercise

Example Output:

Share this C++ Exercise