Windows API Guide: IP Address Control Window Class


Declare Function Process32First Lib "kernel32.dll" (ByVal hSnapshot As Long, lppe As PROCESSENTRY32) As Long

Platforms

  • Windows 95: Supported.
  • Windows 98: Supported.
  • Windows NT: Not Supported.
  • Windows 2000: Supported.
  • Windows CE: Not Supported.

Description & Usage

Process32First retrieves information about the first process in the process list contained in a system snapshot. This snapshot must have previously been generated using the CreateToolhelp32Snapshot function.

Return Value

If successful, the function returns a nonzero value. If an error occured, possibly if there is an empty or nonexistent process list in the snapshot, the function returns zero.

Visual Basic-Specific Issues

None.

Parameters

hSnapshot
A handle to the system snapshot created by the CreateToolhelp32Snapshot function. This snapshot contains the process list from which the first process is read.
lppe
Receives information about the first process in the snapshot. The dwSize member of this structure must be initialized before calling the function.

Example

Print a list of all the processes currently running on the computer when the user clicks button Command1. To do this, a snapshot of the running process list is taken, and then each process in it is analyzed. The filename of the process and the number of threads owned by it is then displayed. To use this example, place a command button named Command1 on a form window.

' This code is licensed according to the terms and conditions listed here. ' Declarations and such needed for the example: ' (Copy them to the (declarations) section of a module.) Public Declare Function CreateToolhelp32Snapshot Lib "kernel32.dll" (ByVal dwFlags As Long, ByVal _ th32ProcessID As Long) As Long Public Const TH32CS_SNAPPROCESS = &H2 Public Type PROCESSENTRY32 dwSize As Long cntUsage As Long th32ProcessID As Long th32DefaultHeapID As Long th32ModuleID As Long cntThreads As Long th32ParentProcessID As Long pcPriClassBase As Long dwFlags As Long szExeFile As String * 260 End Type Public Declare Function Process32First Lib "kernel32.dll" (ByVal hSnapshot As Long, _ lppe As PROCESSENTRY32) As Long Public Declare Function Process32Next Lib "kernel32.dll" (ByVal hSnapshot As Long, _ lppe As PROCESSENTRY32) As Long Public Declare Function CloseHandle Lib "kernel32.dll" (ByVal hObject As Long) As Long ' *** Place the following code inside a form window. *** Private Sub Command1_Click() Dim hSnapshot As Long  ' handle to the snapshot of the process list Dim processInfo As PROCESSENTRY32  ' information about a process in that list Dim success As Long    ' success of having gotten info on another process Dim exeName As String  ' filename of the process Dim retval As Long     ' generic return value ' First, make a snapshot of the current process list. hSnapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0) ' Get information about the first process in the list. processInfo.dwSize = Len(processInfo) success = Process32First(hSnapshot, processInfo) ' Make sure a handle was returned. If hSnapshot = -1 Then Debug.Print "Unable to take snapshot of process list!" Exit Sub End If ' Loop for each process on the list. While success <> 0 ' Extract the filename of the process (i.e., remove the empty space) exeName = Left(processInfo.szExeFile, InStr(processInfo.szExeFile, vbNullChar) - 1) ' Display the process name and the number of threads it owns. Debug.Print "Process: "; exeName Debug.Print "  - Number of threads:"; processInfo.cntThreads ' Get information about the next process, if there is one. processInfo.dwSize = Len(processInfo) success = Process32Next(hSnapshot, processInfo) Wend ' Destroy the snapshot, now that we no longer need it. retval = CloseHandle(hSnapshot) End Sub

See Also

Process32Next

Category

Tool Help

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Last Modified: September 24, 2000
This page is copyright © 2000 Paul Kuliniewicz. Copyright Information Revised October 29, 2000
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Windows API Guide
Windows API Guide - Reference - Volume 1: Version 3.0 For the MS-DOS and PC-DOS Operating Systems
ISBN: B001V0KQIY
EAN: N/A
Year: 1998
Pages: 610

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