The alpha() function evaluates the expression and returns 1 (true) if every character in the string is alphabetical (that is, a—z upper and lowercase), or 0 (false) if any character is nonalphabetical.
The empty (null) string ("") is considered nonalphabetical.
|exp||String to be tested for the existence of alphabetical characters.|
If the value of the variable, response, is made up of only alpha characters, it is assigned to the first element of array.
if alpha(response) then array(1) = response