HOWTO: Access Child Process Exit Code from 32-Bit Parent Process

• The C Run-Time (CRT), included with:
  • Microsoft Visual C++, 32-bit Editions, versions 2.0, 2.1, 4.0, 5.0, 6.0

SUMMARY

In the Microsoft products listed at the beginning of this article, there is no C run-time function that will return the system exit code from a child process. However, the Win32 GetExitCodeProcess() API function can retrieve this information. This article shows how to use it.

MORE INFORMATION

Under Win32, the GetExitCodeProcess() function retrieves the exit status of the child process. In fact, GetExitCodeProcess() can retrieve the exit status of any process given the correct process handle. The process handle itself must have PROCESS_QUERY_INFORMATION access before it can be used.

If the specified process has not terminated, STILL_ACTIVE is returned as the exit status. If the process has terminated, the exit status returned is one of these:

• The exit value specified in the ExitProcess or TerminateProcess function.


-or-


• The return value from the main or WinMain function of the process.


-or-


• The exception value for an unhandled exception that caused the process to terminate.

Sample Code

/* Compile options needed: none
*/ 

#include <windows.h>
#include <stdio.h>

void main(void)
{
   PROCESS_INFORMATION pInfo;
   STARTUPINFO         sInfo;
   DWORD               exitCode;

   sInfo.cb              = sizeof(STARTUPINFO);
   sInfo.lpReserved      = NULL;
   sInfo.lpReserved2     = NULL;
   sInfo.cbReserved2     = 0;
   sInfo.lpDesktop       = NULL;
   sInfo.lpTitle         = NULL;
   sInfo.dwFlags         = 0;
   sInfo.dwX             = 0;
   sInfo.dwY             = 0;
   sInfo.dwFillAttribute = 0;
   sInfo.wShowWindow     = SW_SHOW;

   if (!CreateProcess(NULL,
                "command.com /c dir c:\\*.bat",
                      NULL,
                      NULL,
                      FALSE,
                      0,
                      NULL,
                      NULL,
                      &sInfo,
                      &pInfo)) {
      printf("ERROR: Cannot launch child process\n");
      exit(1);
   }

   // Give the process time to execute and finish
   WaitForSingleObject(pInfo.hProcess, 5000L);

   if (GetExitCodeProcess(pInfo.hProcess, &exitCode))
   {
      switch(exitCode)
      {
         case STILL_ACTIVE: printf("Process is still active\n");
                            break;
         default:           printf("Exit code = %d\n", exitCode);
                            break;
      }
   }
   else {
      printf("GetExitCodeProcess() failed\n");
   }
} 

REFERENCES

Books Online documentation for the Win32 GetExitCodeProcess() function.

For information about 16-bit MS-DOS-based programs, please see the following article in the Microsoft Knowledge Base:

Q58437 Accessing Child Process Exit Code from 16-Bit Parent Process

Q83301 Retrieving Application Exit Code in MS-DOS Window

Additional query words: 9.00 9.0 9.1 9.10

Keywords          : kbcode kbCRT kbVC200 kbVC210 kbVC400 kbVC500 kbVC600 
Version           : WINNT: 2.0,2.1,4.0,5.0;
Platform          : NT WINDOWS 
Issue type        : kbhowto 

Last Reviewed: July 21, 1999