Example: Count Vowels Consonants Digits in C

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

int main() {
    char str[100];
    int vowels = 0;
    int consonants = 0;
    int digits = 0;
    int i;

    // Step 1: Get input string from the user
    printf("Enter a string: ");
    fgets(str, sizeof(str), stdin); // Reads string including spaces

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

    // Step 2: Iterate through each character of the string
    for (i = 0; str[i] != '\0'; i++) {
        char ch = str[i];

        // Step 3: Check if the character is a digit
        if (ch >= '0' && ch <= '9') {
            digits++;
        }
        // Step 4: Check if the character is an alphabet
        else if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')) {
            // Convert to lowercase for consistent vowel checking
            ch = tolower(ch);

            // Step 5: Check if the lowercase alphabet is a vowel
            if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u') {
                vowels++;
            }
            // Step 6: Otherwise, it's a consonant
            else {
                consonants++;
            }
        }
        // Characters that are not digits or alphabets (e.g., spaces, punctuation) are ignored.
    }

    // Step 7: Print the final counts
    printf("Number of Vowels: %d\n", vowels);
    printf("Number of Consonants: %d\n", consonants);
    printf("Number of Digits: %d\n", digits);

    return 0;
}