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 DECLARE FUNCTION name [CDECL] [ALIAS "aliasname"] [([parameterlist])]
 DECLARE SUB name [CDECL] [ALIAS "aliasname"] [([parameterlist])]
 
 Usage Notes
   ■ The CDECL passes the arguments from right to left, rather than using the
     Visual Basic convention of left to right.
 
   ■ CDECL also affects the name used in searches of object files and
     libraries:
     • If there is no ALIAS clause in the DECLARE statement, the type-
       declaration character is removed from the name of the procedure, and
       an underscore is added to the beginning. This becomes the name used
       when searching libraries and external files.
     • If CDECL is used with ALIAS, aliasname is used as is.
 
   ■ BYVAL can be used only with INTEGER, LONG, SINGLE, DOUBLE, and CURRENCY
     types. When BYVAL appears in front of a parameter, the actual argument
     is converted to the type indicated in the DECLARE statement before being
     passed. The additional data types, FORM and CONTROL, can only be used
     when a form or control is passed as an argument to a SUB or FUNCTION
     procedure.
 
   ■ If the variable is an array, it can be followed by the number of
     dimensions in parentheses to maintain compatibility with earlier
     versions of Microsoft Basic. For example:
 
         DECLARE SUB EigenValue (A(2) AS DOUBLE)
 
   ■ You also can indicate the variable type for parameterlist by either:
     • Including an explicit type-declaration character (%, &, !, @, #, or
       $) in the variable name
     • Relying on the default type
 
   ■ When declaring external procedures written in other languages, you can
     use the ANY keyword in the AS clause. ANY overrides type checking for
     that argument. You cannot use ANY with arguments passed by value.
 
   ■ When neither BYVAL nor SEG is used, arguments are passed as near
     addresses (offsets).
 
   ■ This form of the DECLARE statement allows you to refer to procedures
     written in other languages.
 
   ■ The DECLARE statement causes the compiler to check the number and type
     of arguments used to invoke the procedure.
 
   ■ A DECLARE statement can appear only in module-level code and affects
     the entire source file.
 
   ■ The form of parameterlist determines whether or not argument type
     checking is done, as described in the following declarations:
 
     Example                              Description
     ═══════════════════════════════════  ══════════════════════════════════
     DECLARE SUB First CDECL              No argument checking is done when
                                          there is no parameter list.
     DECLARE SUB First CDECL ( )          First has no parameters. Arguments
                                          in a call to First generate an
                                          error; empty parentheses indicate
                                          that SUB or FUNCTION has no
                                          parameters and that argument
                                          checking should be done.
     DECLARE SUB First CDECL (X AS LONG)  First takes one long integer
                                          argument. When an argument list
                                          appears, the number and type of the
                                          arguments are checked in each
                                          invocation.
 
   ■ A procedure that appears in a DECLARE statement can be invoked without
     the CALL keyword.
 
   ■ You cannot have fixed-length strings in DECLARE statements because only
     variable-length strings can be passed to SUB and FUNCTION procedures.
     Fixed-length strings can appear in an argument list but are converted
     to variable-length strings before being passed.
 
   ■ Be careful when using the SEG keyword, because Visual Basic may move
     variables in memory before the called routine begins execution. Anything
     in a CALL statement's argument list that causes memory movement may
     create problems. You can safely pass variables using SEG if the CALL
     statement's argument list contains only simple variables or arithmetic
     expressions.
 
   ■ You cannot pass arrays using the SEG keyword.