This article was previously published under Q187913
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SUMMARY
This article illustrates how you can list the processes that are currently
running on a computer. The approach is different for Windows 95/98 and
Windows NT; this article illustrates both solutions.
This situation requires that you first test to see which version of Windows
is in use. Once that determination is made, the correct code can then be
run to examine and list the current processes. On Windows NT, requests for
information on some system processes may be denied for security or other
related reasons. The approach taken in this article will ignore any process
that cannot be accessed.
PSAPI.DLL is the library used to gather process information on Windows NT
and must reside in the \SYSTEM32 directory. There are two versions of this
file, 3.51 and 4.0. Either version will work for this example, but using
the most recent version is recommended. If you have installed the Windows
NT 4.0 Resource Kit or the Windows NT 4.0 SDK, this file will be present on
your computer. The 4.0 version of the file is available on the Visual
Studio Visual C++ CD-ROM in the following directory:
\DEVSTUDIO\VC\BIN\PSAPI.DLL.
The 3.51 version of the file is available on the Visual Studio Visual Basic
CD-ROM in the directory:
Create a new Standard Exe project in Visual Basic. Form1 is created by
default.
2.
Add a CommandButton to Form1.
3.
Add a ListBox to Form1.
4.
Copy the following code to Form1:
Option Explicit
Private Sub Command1_Click()
List1.Clear
Select Case getVersion()
Case 1 'Windows 95/98
Dim f As Long, sname As String
Dim hSnap As Long, proc As PROCESSENTRY32
hSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0)
If hSnap = hNull Then Exit Sub
proc.dwSize = Len(proc)
' Iterate through the processes
f = Process32First(hSnap, proc)
Do While f
sname = StrZToStr(proc.szExeFile)
List1.AddItem sname
f = Process32Next(hSnap, proc)
Loop
Case 2 'Windows NT
Dim cb As Long
Dim cbNeeded As Long
Dim NumElements As Long
Dim ProcessIDs() As Long
Dim cbNeeded2 As Long
Dim NumElements2 As Long
Dim Modules(1 To 200) As Long
Dim lRet As Long
Dim ModuleName As String
Dim nSize As Long
Dim hProcess As Long
Dim i As Long
'Get the array containing the process id's for each process object
cb = 8
cbNeeded = 96
Do While cb <= cbNeeded
cb = cb * 2
ReDim ProcessIDs(cb / 4) As Long
lRet = EnumProcesses(ProcessIDs(1), cb, cbNeeded)
Loop
NumElements = cbNeeded / 4
For i = 1 To NumElements
'Get a handle to the Process
hProcess = OpenProcess(PROCESS_QUERY_INFORMATION _
Or PROCESS_VM_READ, 0, ProcessIDs(i))
'Got a Process handle
If hProcess <> 0 Then
'Get an array of the module handles for the specified
'process
lRet = EnumProcessModules(hProcess, Modules(1), 200, _
cbNeeded2)
'If the Module Array is retrieved, Get the ModuleFileName
If lRet <> 0 Then
ModuleName = Space(MAX_PATH)
nSize = 500
lRet = GetModuleFileNameExA(hProcess, Modules(1), _
ModuleName, nSize)
List1.AddItem Left(ModuleName, lRet)
End If
End If
'Close the handle to the process
lRet = CloseHandle(hProcess)
Next
End Select
End Sub
5.
Add a Standard Module to the Project. Module1 is created.
6.
Paste the following code into Module1.
Public Declare Function Process32First Lib "kernel32" ( _
ByVal hSnapshot As Long, lppe As PROCESSENTRY32) As Long
Public Declare Function Process32Next Lib "kernel32" ( _
ByVal hSnapshot As Long, lppe As PROCESSENTRY32) As Long
Public Declare Function CloseHandle Lib "Kernel32.dll" _
(ByVal Handle As Long) As Long
Public Declare Function OpenProcess Lib "Kernel32.dll" _
(ByVal dwDesiredAccessas As Long, ByVal bInheritHandle As Long, _
ByVal dwProcId As Long) As Long
Public Declare Function EnumProcesses Lib "psapi.dll" _
(ByRef lpidProcess As Long, ByVal cb As Long, _
ByRef cbNeeded As Long) As Long
Public Declare Function GetModuleFileNameExA Lib "psapi.dll" _
(ByVal hProcess As Long, ByVal hModule As Long, _
ByVal ModuleName As String, ByVal nSize As Long) As Long
Public Declare Function EnumProcessModules Lib "psapi.dll" _
(ByVal hProcess As Long, ByRef lphModule As Long, _
ByVal cb As Long, ByRef cbNeeded As Long) As Long
Public Declare Function CreateToolhelp32Snapshot Lib "kernel32" ( _
ByVal dwFlags As Long, ByVal th32ProcessID As Long) As Long
Public Declare Function GetVersionExA Lib "kernel32" _
(lpVersionInformation As OSVERSIONINFO) As Integer
Public Type PROCESSENTRY32
dwSize As Long
cntUsage As Long
th32ProcessID As Long ' This process
th32DefaultHeapID As Long
th32ModuleID As Long ' Associated exe
cntThreads As Long
th32ParentProcessID As Long ' This process's parent process
pcPriClassBase As Long ' Base priority of process threads
dwFlags As Long
szExeFile As String * 260 ' MAX_PATH
End Type
Public Type OSVERSIONINFO
dwOSVersionInfoSize As Long
dwMajorVersion As Long
dwMinorVersion As Long
dwBuildNumber As Long
dwPlatformId As Long '1 = Windows 95.
'2 = Windows NT
szCSDVersion As String * 128
End Type
Public Const PROCESS_QUERY_INFORMATION = 1024
Public Const PROCESS_VM_READ = 16
Public Const MAX_PATH = 260
Public Const STANDARD_RIGHTS_REQUIRED = &HF0000
Public Const SYNCHRONIZE = &H100000
'STANDARD_RIGHTS_REQUIRED Or SYNCHRONIZE Or &HFFF
Public Const PROCESS_ALL_ACCESS = &H1F0FFF
Public Const TH32CS_SNAPPROCESS = &H2&
Public Const hNull = 0
Function StrZToStr(s As String) As String
StrZToStr = Left$(s, Len(s) - 1)
End Function
Public Function getVersion() As Long
Dim osinfo As OSVERSIONINFO
Dim retvalue As Integer
osinfo.dwOSVersionInfoSize = 148
osinfo.szCSDVersion = Space$(128)
retvalue = GetVersionExA(osinfo)
getVersion = osinfo.dwPlatformId
End Function
7.
Run the project and click the Command button on Form1. You should
see a listing of the currently running processes.
8.
If you are running Windows 95/98, try running the example project on
Windows NT or vice versa. The processes should be listed regardless
of operating system version.
Portions of the code in this article were adapted from "Hardcore Visual
Basic" Second Edition by Bruce McKinney - Microsoft Press
For additional information on the GetVersionExA API, please see the
following article in the Microsoft Knowledge Base:
189249 (http://support.microsoft.com/kb/189249/EN-US/)
: How To Determine Which 32-bit Operating System Is Being Used
For additional information on using PSAPI.DLL, please see the Microsoft
Systems Journal "Under the Hood" column by Matt Pietrek (August 1996 and
November 1996)
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