How to check if a program is running by its name with Qt (C++)

Question

How to check if a program is running, by its name, with Qt (C++).

Will QProcess::pid do the job? I don't know how to use it. Please suggest.

Solution 1

As far as I know QProcess won't allow you to do that (unless you've spawned the process yourself) and in fact nothing in Qt will. However Win32 API provides a way to achieve what you want through EnumProcesses function and a complete example of how to use it is provided at Microsoft website:

http://msdn.microsoft.com/en-us/library/ms682623.aspx

To get you need replace PrintProcessNameAndID with the following function:

bool matchProcessName( DWORD processID, std::string processName)
{
    TCHAR szProcessName[MAX_PATH] = TEXT("<unknown>");

    // Get a handle to the process.

    HANDLE hProcess = OpenProcess( PROCESS_QUERY_INFORMATION |
                                   PROCESS_VM_READ,
                                   FALSE, processID );

    // Get the process name.

    if (NULL != hProcess )
    {
        HMODULE hMod;
        DWORD cbNeeded;

        if ( EnumProcessModules( hProcess, &hMod, sizeof(hMod), 
             &cbNeeded) )
        {
            GetModuleBaseName( hProcess, hMod, szProcessName, 
                               sizeof(szProcessName)/sizeof(TCHAR) );
        }
    }

    // Compare process name with your string        
    bool matchFound = !_tcscmp(szProcessName, processName.c_str() );

    // Release the handle to the process.    
    CloseHandle( hProcess );

    return matchFound;
}

Solution 2

A quick and dirty way to do it would be to just check the output of tasklist, something like:

bool isRunning(const QString &process) {
  QProcess tasklist;
  tasklist.start(
        "tasklist",
        QStringList() << "/NH" 
                      << "/FO" << "CSV" 
                      << "/FI" << QString("IMAGENAME eq %1").arg(process));
  tasklist.waitForFinished();
  QString output = tasklist.readAllStandardOutput();
  return output.startsWith(QString("\"%1").arg(process));
}

Using EnumProcesses is probably a better way (i.e. more "pure"; certainly more performant), but this may be "good enough" as long as this isn't being called in a big loop or something. The same idea could also be ported to other platforms as well, although obviously the command tool and parsing logic would be different.

Comments

[Dave Mateer]

+1 to compensate for the downvote; not sure why this was downvoted. I was going to include a link to the same page in my response. This is certainly the official way to do it.

[Willy K.]

This is not the answer to the question "How to check if a program is running.... But thanks for your input anyhow.