Tip 97: Creating a Task List

Abstract
This article explains how you can determine what modules are currently
running under Microsoft® Windows® and create a task list based on that
information.

Determine What Modules Are Currently Running
The TOOLHELP.DLL dynamic-link library (.DLL) file contains two
Windows® application programming interface (API) functions that can be
used to create a list of modules currently loaded under Windows. These
are the ModuleFirst and ModuleNext functions. To declare these
functions within your program, include the following Declare
statements in the Global Module or General Declarations section of a
Visual Basic® form:

Private Declare Function ModuleFirst Lib "toolhelp.dll" (mdlentry As
ModuleEntry) As Integer
Private Declare Function ModuleNext Lib "toolhelp.dll" (mdlentry As ModuleEntry)
As Integer

Note that each Declare statement must be typed as a single line of text.
The ModuleFirst and ModuleNext functions are the key to traversing
the chain of loaded modules in Windows. The ModuleFirst function fills
the specified structure with information describing the first module
in the list of currently loaded modules. The ModuleNext function is
then called to find the next module in the list.

The MODULEENTRY structure required by these two functions must be
defined as follows:

dwSize The size of the structure in bytes.
szModule The module's name (a null-terminated string).
hModule The module's handle.
wcUsage Used by GetModuleUsage function.
szExePath The module.
wNext The window.

Before you can use these two functions, however, you must initialize
the dwSize field of the MODULEENTRY structure. This value should be
specified as the number of bytes needed to store the information
returned by ModuleFirst and ModuleNext.
These functions return a value indicating the status of the function.
The function was successful if the returned value is nonzero; the
function was not successful (or no more modules were found in memory)
if the value returned is zero.

Example Program
This program shows how to retrieve the module name and path for every
running task under Windows. The name of each module is displayed in
the first List Box control, while the full path of the module is
displayed in the second List Box control.

1. Create a new project in Visual Basic. Form1 is created by default.
2. Add the following code to the General Declarations section of
Form1 (note that each Declare statement should be typed as a
single line of text):

Private Declare Function ModuleFirst Lib "toolhelp.dll" (mdlentry As
ModuleEntry) As Integer
Private Declare Function ModuleNext Lib "toolhelp.dll" (mdlentry As ModuleEntry)
As Integer

3. Add a Command Button control to Form1. Add the following code to
the Click event for Command1:

Private Sub Command1_Click()
Dim Tmp As ModuleEntry
Dim Retn As Integer

Tmp.dwSize = Len(Tmp)
Retn = ModuleFirst(Tmp)
While Retn <> 0
If InStr(Tmp.szExepath, ".VBX") <> 0 Or InStr(Tmp.szExepath, ".DLL") <>
0 Or InStr(Tmp.szExepath, ">DRV") <> 0 Then
List1.AddItem Tmp.szModule
List2.AddItem Tmp.szExepath
End If
Tmp.szExepath = ""
Retn = ModuleNext(Tmp)
Wend
End Sub

4. Add a List Box control to Form1. List1 is created by default.
5. Add a second List Box control to Form1. List2 is created by
default.
6. From the Insert menu, select Module. Module1.Bas is created by
default.
7. Add the following user-defined Type to Module1.Bas:

Type ModuleEntry
dwSize As Long
szModule As String * 10
hModule As Integer
wcUsage As Integer
szExepath As String * 256
wNext As Integer
End Type

Additional References

Knowledge Base Q78001. "How to Get Windows Master (Task List) Using
Visual Basic."
Knowledge Base Q80124. "Retrieving the Names of Simultaneous Tasks
Under Windows."
"Windows Questions and Answers." (Books and Periodicals, Microsoft
Systems Journal, 1994 Volume 9, May 1994 Number 5)