DECLARE FUNCTION / DECLARE SUB

See also Example

Declaration of an external function or subroutine. This instruction is used whenever a DLL call is to be made.

WebVue support - Yes.

Mode	Mnemonic	Syntax
-	FUNCTION	1
-	SUB	2

Syntax 1

DECLARE FUNCTION GlobalName LIB Libname [ALIAS AliasName] ([Arguments]) AS Type;

Argument	Meaning
GlobalName	The name by which the SUB or FUNCTION will be known. If different to the real name of the SUB or FUNCTION in the DLL then the AliasName must also be specified.
LibName	The name of the DLL where the declared function is to be found. Type STR. If executed in a WebVue session context this instruction is processed by the computer that hosts the web back end. The DLL must be present on the computer that hosts the web back end.
AliasName	The name of the function in the DLL if different to the name that it will be known by in the program (as specified by the GlobalName parameter). Type STR.
Type	The type returned by the function (INTEGER, LONG, SINGLE, DOUBLE or STR).
Arguments	An argument list with the following syntax:
	[BYVAL] Variable AS Type, [BYVAL] Variable AS Type, ...
Variable	The name of the variable passed as an argument.
Type	The type of the variable passed as an argument. INTEGER, LONG, SINGLE, DOUBLE.

Execution

The external program behaves as a function. It always returns a value.

Syntax 2

DECLARE SUB GlobalName LIB LibName [ALIAS AliasName] ([Arguments]);

Execution

The external program behaves as a subroutine. It does not return a value.

Example

DECLARE SUB DosBeep lib "DOSCALLS" (X as integer);

DECLARE FUNCTION WinExec LIB "KERNEL" (BYVAL File AS STR,BYVAL SH AS INTEGER) AS INTEGER;