Click here to Skip to main content
15,505,126 members
Articles / Programming Languages / C++
Posted 20 Mar 2005


21 bookmarked

Get Parent Process PID

Rate me:
Please Sign up or sign in to vote.
3.19/5 (13 votes)
22 Mar 20052 min read
How to get the parent process PID, and how to use it in the child process.

Sample Image


Sometimes, you might be in a situation when your application is launched by another program, which cannot be modified to change its behavior.

If you can not grab any COM interface or a meaningful Windows handle, then the only thing left is the process handle to deal with. One thing you can do with such a handle is to try to do some interprocess synchronization.

There are two programs included in the workspace, a startup MFC application that will merely launch the child, and the child application called GetParentProcID.exe that will latch onto its parent and wait for its termination.


Unfortunately, Win32 does not have an API that gives you the PID of the parent process, and you have to create it yourself. We will use functions found in Psapi.dll and in the Kernel32.DLL, that will be loaded programmatically.

Using the code

In short, we need to iterate through the processes running on the machine, identify the current process entry, and use it to retrieve the parent’s PID.

We begin by getting the handle to a Toolhelp snapshot of the systems.

hSnapShot = lpfCreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0 );

This handle is used to iterate through the process entries and compare them against the current process ID:

bContinue = lpfProcess32First( hSnapShot, &procentry ) ;
DWORD pid = 0;
    // While there are processes, keep looping.
DWORD  crtpid= GetCurrentProcessId();
    while( bContinue )
   if(crtpid == procentry.th32ProcessID)
       pid =  procentry.th32ParentProcessID;

          procentry.dwSize = sizeof(PROCESSENTRY32) ;
          bContinue = !pid && lpfProcess32Next( hSnapShot, &procentry );
    }//while ends

The PROCESSENTRY32 structure we got from our GetParentProcID function is passed down to the WaitForParentToFinish, that does the synchronization:

The parent process PID is the th32ParentProcessID data member of this structure.

There are two things to note about this last function:

  1. We need to get a process handle that can be used for synchronization (hence the SYNCHRONIZE flag):
    HANDLE hProcess = OpenProcess(
                   FALSE, procentry.th32ParentProcessID ) ;
  2. The parent’s file name can be retrieved using EnumProcessModules and grabbing the name from the first module by calling GetModuleFileNameEx:
    if( EnumProcessModules( hProcess, &hMod, sizeof( hMod ), &dwSize2 ) )
        if( !GetModuleFileNameEx( hProcess, hMod,
                    szFileName, sizeof( szFileName ) ) )

Once we have all the info about the parent, we can wait for its termination by calling WaitForSingleObject:

while(dwres = WaitForSingleObject(hProcess,
            TIMEOUT) == WAIT_TIMEOUT)//wait up to TIMEOUT ms
    printf("TimedOut waiting for %s after %d ms\n", pszName,TIMEOUT);
printf((WAIT_OBJECT_0 == dwres)?
  "waiting for parent termination SUCCEEDED\n" :
  "parent waiting FAILED\n");


This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

Written By
Software Developer (Senior)
United States United States
Decebal Mihailescu is a software engineer with interest in .Net, C# and C++.

Comments and Discussions

QuestionPermission for usage of this code snippet Pin
Member 138985094-Jul-18 6:43
Member 138985094-Jul-18 6:43 
QuestionhSnapShot not released Pin
baniaczek31-Oct-13 20:09
baniaczek31-Oct-13 20:09 
Generalmybe issue path ! [modified] Pin
masonzhang197719-Mar-10 23:15
masonzhang197719-Mar-10 23:15 
QuestionSorry Pin
Gzd200722-Aug-06 23:05
Gzd200722-Aug-06 23:05 
GeneralI can not compile the program! Pin
Gzd200722-Aug-06 23:03
Gzd200722-Aug-06 23:03 
GeneralRe: I can not compile the program! Pin
Vytas18-Sep-06 9:47
Vytas18-Sep-06 9:47 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.