C Program to Check Vowel or Consonant

There are five vowel letters in English: a, e, i, o, and u. All other alphabetic letters are consonants.

• The same vowels apply to uppercase letters: A, E, I, O, and U.
• This program checks whether a given character is a vowel or consonant.

Algorithm

The basic algorithm is:

• Take a character as input.
• Check whether the character is one of a, e, i, o, u or their uppercase forms.
• If the character matches any vowel, print Vowel.
• Otherwise, print Consonant.

1. Check Vowel or Consonant Using if-else in C

We can use the logical OR (||) operator to check the character against all five vowels in both lowercase and uppercase.

#include <stdio.h>

// Driver code
int main()
{
    char ch = 'A';

    // Checking if the character ch
    // is a vowel or not.
    if (ch == 'a' || ch == 'A' || ch == 'e' || ch == 'E'
        || ch == 'i' || ch == 'I' || ch == 'o' || ch == 'O'
        || ch == 'u' || ch == 'U') {

        printf("The character %c is a vowel.\n", ch);
    }
    else {
        printf("The character %c is a consonant.\n", ch);
    }

    return 0;
}

The character A is a vowel.

Explanation: The if condition compares the character with all five vowels in both uppercase and lowercase. If any comparison is true, the character is a vowel; otherwise, it is considered a consonant.

2. Check Vowel or Consonant Using strchr() in C

The strchr() function is used to search for the entered character in the vowels array. If the character is found, the isVowel function returns 1, otherwise, it returns 0.

#include <stdio.h>
#include <string.h>

int isVowel(char ch)
{
    // Make the list of vowels
    char vowels[] = "aeiouAEIOU";
    return (strchr(vowels, ch) != NULL);
}

// Driver Code
int main()
{
    if (isVowel('a'))
        printf("a is vowel\n");
    else
        printf("a is consonant\n");
    return 0;
}

a is vowel

Explanation: The strchr() function searches for ch in the string "aeiouAEIOU". If the character is found, strchr() returns a non-NULL pointer, indicating that the character is a vowel.