Tool Help Library makes it easy to enumerate and get info about processes, threads, modules, and heaps. Let’s use it to get a list of running processes.

Using Tool Help Library

First, take a snapshot by passing TH32CS_SNAPPROCESS flag to CreateToolhelp32Snapshot function. Next, pass the snapshot handle to Process32First, then to Process32Next to get running processes info in a list of PROCESSENTRY32 structures.

#include <Tlhelp32.h>

DWORD CDemoDlg::ToolHelp_EnumProcesses(CList<PROCESSENTRY32>& listProcInfo)
{
    DWORD dwRet = NO_ERROR;

    // take a snapshot of processes
    DWORD dwFlags = TH32CS_SNAPPROCESS;
    HANDLE hSnapshot = ::CreateToolhelp32Snapshot(dwFlags, 0);
    if(INVALID_HANDLE_VALUE == hSnapshot)
    {
        return ::GetLastError();
    }

    PROCESSENTRY32 processEntry = {0};
    processEntry.dwSize = sizeof(PROCESSENTRY32);
    // get info for each process in the snapshot
    if(::Process32First(hSnapshot, &processEntry))
    {
        do
        {   
            listProcInfo.AddTail(processEntry);
        }
        while(::Process32Next(hSnapshot, &processEntry));
    }
    else
    {
        dwRet = ::GetLastError();
    }
    ::CloseHandle(hSnapshot);
    return dwRet;
}

Next example fills a listview control with the following info of each process.

• PID (process identifier);
• process image name (the name of the executable file);
• parent PID;
• number of threads started by the process;
• base priority of any threads created by this process.

void CDemoDlg::_FillProcessesList()
{
    // clear listview control
    m_listProcesses.DeleteAllItems();

    // get a list of PROCESSENTRY32 structures
    CList<PROCESSENTRY32> listProcInfo;
    VERIFY(NO_ERROR == ToolHelp_EnumProcesses(listProcInfo));

    // fill the listview control
    POSITION pos = listProcInfo.GetHeadPosition();
    int nIndex = 0;
    while(NULL != pos)
    {
        // get next process from the list
        const PROCESSENTRY32& procInfo = listProcInfo.GetNext(pos);

        // format info strings
        CString strPID, strImageName, strParentPID, strThreads, strPriority;
        strPID.Format(_T("%u"), procInfo.th32ProcessID);
        strImageName = procInfo.szExeFile;
        strParentPID.Format(_T("%u"), procInfo.th32ParentProcessID);
        strThreads.Format(_T("%u"), procInfo.cntThreads);
        strPriority.Format(_T("%d"), procInfo.pcPriClassBase);

        // set listview item text
        m_listProcesses.InsertItem(nIndex, strPID);
        m_listProcesses.SetItemText(nIndex, 1, strImageName);
        m_listProcesses.SetItemText(nIndex, 2, strParentPID);
        m_listProcesses.SetItemText(nIndex, 3, strThreads);
        m_listProcesses.SetItemText(nIndex++, 4, strPriority);
    }
}

Demo project

The demo project is a simple MFC dialog-based application that uses the above functions.
Download: Listing_Processes_Using_Tool_Help_Library.zip (1082 downloads)

Resources

• MSDN: Tool Help Library

See also

• Codexpert blog: Listing Processes – Part 1: Introduction
• Codexpert blog: Listing Processes – Part 2: Using PSAPI
• Codexpert blog: Listing Processes – Part 4: Using Remote Desktop Services API