Tech Tip: Determining if character in a string is a vowel

PRODUCT: 4D | VERSION: 14.3 | PLATFORM: Mac & Win

Published On: May 27, 2015

Below is an utility method to determine if a character in a string is a vowel. Vowels are the characters a,e,i,o,u and sometimes y.

//Method name: isVowel
//Determines if character specified in string is a vowel
//$1 - source string
//$2 - position of string for the character to check
//$0 - True if a constant, false if not

C_TEXT($1;$string) //source string
C_LONGINT($2;$i)   //position of string to check
C_TEXT($char)
C_LONGINT($l)
C_BOOLEAN($0;$isVowel)

If (Count parameters>=2)
  $string:=$1
  $i:=$2
  $l:=Length($string)

  If ($i<=$l) & ($i>0)
    $char:=$string[[$i]]
    Case of
      : ($char="a")|($char="e")|($char="i")|($char="o") | ($char="u") //vowels
        $isVowel:=True
      : ($char="y") //check to see if y is a vowel or a constant
        If ($i=1)   //if y is the first character, y is a constant
          $isVowel:=False
        Else
          If ($i<($l+1))
            $isVowel:=Not(isVowel ($string;$i-1)) //if char before y is a const, y                                                  //is a vowel; else y is a constant
          Else
            $isVowel:=False
          End if
        End if
      Else
        $isVowel:=False
    End case
  End if
  $0:=$isVowel
End if

Example:

$string:="apple"
$isVowel:=isVowel($string;1) //returns true
$isVowel:=isVowel($string;2) //returns false

$string:="yak"
$isVowel:=isVowel($string;1) //returns false

$string:="myth"
$isVowel:=isVowel($string;2)//returns true

Commented by Keith Culotta on June 4, 2015 at 10:13 AM

Consonant