CFLib.org – Common Function Library Project

Description:
Returns the numeric value of a letter's position in the alphabet, or returns the matching letter of a number in the alphabet.

Return Values:
Returns either a character, number, or empty string on error.

Example:

<cfoutput>
The 3rd letter in the alphabet is #GetAlphabetPosition(3)#<br>
The 26th letter in the alphabet is #GetAlphabetPosition(26)#<br>
"M" is the #GetAlphabetPosition("M")#(th/rd) letter in the alphabet.<br>
"Z" is the #GetAlphabetPosition("Z")#(th/rd) letter in the alphabet.<br>
</cfoutput>

Parameters:

Full UDF Source:

/**
 * Returns the numeric value of a letter's position in the alphabet, or the returns matching letter of a number in the alphabet.
 * 
 * @param charornum      Either a character or number. 
 * @return Returns either a character, number, or empty string on error. 
 * @author Seth Duffey (sduffey@ci.davis.ca.us) 
 * @version 1, January 7, 2002 
 */
function GetAlphabetPosition(charornum) {
  var a_numeric = asc("a");
  charornum = lCase(trim(charornum));

  if(isNumeric(charornum)) {
      if(charornum lte 0 OR charornum gte 27) return "";
      return chr(charornum+a_numeric-1);
  } else {
      if(len(charornum) gt 1) return "";
      if(REFind("[^a-z]",charornum)) return "";
      return asc(charornum) - a_numeric + 1;
  }
  return 1;
}