CallDllFunction()

Summary

Calls a function in a Dynamic Link Library (DLL).

 

Changes

Optional options array added in Version 5.0.

 

Syntax

ret_val = CallDllFunction(string dll_name, string func_name, string ret_type, array args [, array options])

 

Argument	Contents
dll_name	The name of the Dynamic Link Library (DLL)
func_name	The name of the function to call in the DLL
ret_type	The type of value to return: "int", "double", "string" or null
args	An array of arguments to pass to the function

 

Option	Type	Contents
StdCall	Boolean	If "true" assumes the _stdcall calling convention, where arguments are passed on the stack and the called function is responsible for removing them off the stack; default is "false"
FastCall	Boolean	If "true" assumes the _fastcall calling convention, where some arguments are passed in registers and the called function is responsible for popping other arguments off the stack; default is "false"
Cdecl	Boolean	Assumes the _cdecl calling convention, where the arguments are passed on the stack and the and the calling function is responsible for removing them off the stack; defaultis  "true"

 

Returns

A value of the type specified by ret_type.

 

Notes

• The options array is an optional argument.

• You can replace calls to CallDllFunction() by using the new, closely related LoadLibrary() function.

• Each member of args must be either an integer, double, string, null, or array of longs or doubles (all the same type).

• Values in the arrays will be replaced by their values after the call.

• Any args value that will be filled in must be created first.

• In 64-bit programs the calling convention option is ignored, since all 64-bit programs use the equivalent of the FastCall calling convention.

• In a 32-bit environment, all Standard Windows API functions use StdCall.

Notes on the New Argument Convention

Arguments can be passed in one of two ways:

1. New style: each member of the array is a pair: {type, argument}, where type is a string describing the argument: "short", "long", "float", "double" or "string", meaning the argument is of that type. The type can be succeeded by one or more "*", meaning the argument is an array of that type, two stars mean it's an array of arrays (all of same length), etc. The type can be preceded by "const ", see below.

2. Old style: each member of args must be either an integer, double, string, null, or array of longs or doubles (all same type) - corresponding to long, double, char*, null, long* or double*.

The values in the arrays will be replaced by their values after the call, except when they are of type "const".

 

Example

// Initialize an string

str = null

for i = 1 to 200 do

    str = str + " "

    end

 

// Windows API uses StdCall

opts = {{"StdCall", "True"}}

// Call a function in kernel32.dll

Ret = CallDllFunction("kernel32", "GetSystemDirectoryA", "int", {str, 200}, opts)

ShowArray({Ret, str})

 

Error Codes

Error Type	Meaning
Error	An invalid parameter was specified
NotFound	The DLL or one of its required components was not found or could not be loaded

 

See Also

Function	Summary
LaunchProgram()	Starts a Windows program
LaunchDocument()	Open a document, executable, or URL with the appropriate program
LoadLibrary()	Loads a DLL and returns a handle that can be used in function calls