C Program to Check Whether a Character is a Vowel or Consonant

#include <stdio.h>
#include <ctype.h>  // for using tolower() function

int main() {
    char ch;

    // Input a character from the user
    printf("Enter a character: ");
    scanf("%c", &ch);

    // Convert the character to lowercase to simplify comparisons
    ch = tolower(ch);

    // Check if the character is a vowel or consonant
    if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u') {
        printf("%c is a vowel.\n", ch);
    } else if ((ch >= 'a' && ch <= 'z')) {  // Check if it's a letter
        printf("%c is a consonant.\n", ch);
    } else {
        printf("%c is not a letter.\n", ch);
    }

    return 0;
}

Explanation:

1. tolower() function: Used to convert the character to lowercase, so we only need to check for vowels in lowercase.
2. Vowel check: We check if the character is one of ‘a’, ’e’, ‘i’, ‘o’, or ‘u’.
3. Consonant check: If the character is a letter but not a vowel, it is a consonant.
4. If the input is not a letter (i.e., not in the range ‘a’ to ‘z’), the program informs that it is not a letter.

You can run this program and input a character to see whether it’s a vowel or consonant.

Example 1: Input and Output

Input:

Enter a character: A

Output:

a is a vowel.

Example 2: Input and Output

Input:

Enter a character: b

Output:

b is a consonant.

Example 3: Input and Output

Input:

Enter a character: 1

Output:

1 is not a letter.

How it works:

• Example 1: The user inputs ‘A’, which is converted to lowercase ‘a’. The program identifies ‘a’ as a vowel.
• Example 2: The user inputs ‘b’, and since ‘b’ is a consonant, the program identifies it correctly.
• Example 3: The user inputs ‘1’, which is not a letter, so the program indicates that it’s not a letter.