F_IS_ALPHABET

//Function Name : f_Is_Alphabet
//Argument Name : as_source, Arg Type : String, Pass By : Value
//Return Type : Boolean
//                    True if the string only contains alphabetic characters.
//                    If any argument's value is NULL, function returns NULL.
//
//Description:  Determines whether a string contains only alphabetic
//                   characters.

long        ll_count=0
long        ll_length
char        lc_char[]
integer    li_ascii

//Check parameters
If IsNull(as_source) Then
    boolean lb_null
    SetNull(lb_null)
    Return lb_null
End If

//Get the length
ll_length = Len (as_source)

//Check for at least one character
If ll_length=0 Then
    Return False
End If

//Move string into array of chars
lc_char = as_source

//Perform loop around all characters
//Quit loop if Non Alpha character is found
do while ll_count<ll_length
    ll_count ++
    
    //Get ASC code of character.
    li_ascii = Asc (lc_char[ll_count])
    
    // 'A'=65, 'Z'=90, 'a'=97, 'z'=122
    if li_ascii<65 or (li_ascii>90 and li_ascii<97) or li_ascii>122 then
        /* Character is Not an Alpha */
        Return False
    end if
loop
    
// Entire string is alpha.
return True