Example: Count Vowels and Consonants in C

// Count Vowels and Consonants
#include <stdio.h>
#include <string.h> // For strlen()
#include <ctype.h>  // For isalpha() and tolower()

int main() {
    // Step 1: Declare and initialize a string and counters
    char str[100];
    int vowels = 0;
    int consonants = 0;
    int i;

    // Step 2: Prompt user for input
    printf("Enter a string: ");
    fgets(str, sizeof(str), stdin); // Read string including spaces

    // Remove trailing newline character if present from fgets
    str[strcspn(str, "\n")] = 0; 

    // Step 3: Iterate through the string
    for (i = 0; str[i] != '\0'; i++) {
        // Step 4: Check if the character is an alphabet
        if (isalpha(str[i])) {
            // Step 5: Convert to lowercase for case-insensitive check
            char ch = tolower(str[i]);

            // Step 6: Check if it's a vowel
            if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u') {
                vowels++;
            } else {
                // Step 7: If not a vowel, it's a consonant
                consonants++;
            }
        }
    }

    // Step 8: Print the results
    printf("Number of vowels: %d\n", vowels);
    printf("Number of consonants: %d\n", consonants);

    return 0;
}