Write Salesforce Program to Check Whether an Alphabet is Vowel or Consonant.

Here is an example program in Salesforce Apex code that checks whether a given alphabet is a vowel or consonant:

public class AlphabetChecker {
    public static String checkVowelConsonant(String alphabet) {
        if (alphabet.length() > 1) {
            return 'Please enter a single alphabet.';
        }
        else {
            alphabet = alphabet.toUpperCase();
            if (alphabet == 'A' || alphabet == 'E' || alphabet == 'I' || alphabet == 'O' || alphabet == 'U') {
                return 'Vowel';
            }
            else {
                return 'Consonant';
            }
        }
    }
  }

You can use the above class by instantiating an object of the class and calling the method checkVowelConsonant() and passing a single alphabet as the argument.

AlphabetChecker ac = new AlphabetChecker();
System.debug(ac.checkVowelConsonant('a')); 

This will return "Vowel"

AlphabetChecker ac = new AlphabetChecker();
System.debug(ac.checkVowelConsonant('b')); 

This will return "Consonant"

Please note that the above code assumes that the input is a single alphabet in uppercase or lowercase, if it's not it will throw an error.