Executable return values

[Jim1981]

Is it possible to launch an executable in code using something like CreateProcess, but to make my program wait and not continue until the launched program has closed and returned a value?

I need to launch another .exe and get it's return value when it closes without having to create a client/server type setup.

Cheers.

[vcstarter]

Try shellexecute or shellexecuteex, you should get a return value.

[Jim1981]

Thanks, but as far as I can tell ShellExecute returns right away and doesn't return the value returned by my launched program's main function.

I need my program to wait until the launched program stops running.

Is there a way to do this?

[Richard.J]

under Unix, there is the system() call that does what you want. I don't know right know if there is a similar call under Windows.

[Axter]

Here's a wrapper function that should be able to do what you want:

BOOL ExecuteAndWaitForCompletion ( LPCTSTR pszCmd)
{
	STARTUPINFO si;
	PROCESS_INFORMATION pi;
	
	ZeroMemory ( &si, sizeof ( STARTUPINFO));
	
	si.cb = sizeof ( STARTUPINFO);
	si.dwFlags = STARTF_USESHOWWINDOW;
	si.wShowWindow = SW_HIDE;
	
	bRes     =     CreateProcess ( NULL,
		pszCmd
		NULL,
		NULL,
		TRUE,
		NORMAL_PRIORITY_CLASS,
		GetEnvironmentStrings     (),
		NULL,
		&si,
		&pi
		);
	
	WaitForSingleObject (     pi.hProcess,     INFINITE);
	
	CloseHandle( pi.hProcess);
	CloseHandle( pi.hThread);
	
	return ( bRes);
}

[Andreas Masur]

Well...the first question would be....what operating system are you using? In case of Windows...take a look at the following FAQs:

• How can I start a process?
• How can I wait until a process ends ?

To get the exit code of the process....you can use 'GetExitCodeProcess()'...

[Axter]

How can I start a process?

FYI:
It's strange that the above list of methods seems to exclude the most obvious.

It's excluding the system() function, which is the only C/C++ method defined in the C/C++ standard.

Although _exec and _spawn are in the C run-time library for the VC++ compiler, these two functions are not part of the C/C++ standard. IMHO, the FAQ might lead a newbie to believe that it is part of the C/C++ standard.

I recommend updating the above FAQ to add the system() function, and to clarify that _exec and _spawn are not part of the C/C++ standard.

[Andreas Masur]

I recommend updating the above FAQ to add the system() function, and to clarify that _exec and _spawn are not part of the C/C++ standard.

Besides that this does not belong in this thread...you should have looked at the location of the FAQ. The FAQ is for Windows and not C or C++, thus, there is nothing misleading...nevertheless....since it is only 5 seconds of change...I will add the 'system()' function...

[Axter]

Besides that this does not belong in this thread...you should have looked at the location of the FAQ. The FAQ is for Windows and not C or C++, thus, there is nothing misleading...nevertheless....since it is only 5 seconds of change...I will add the 'system()' function...

I'm not referring to it being misleading because of what thread it's in. If that was the case, I would have mention the other functions listed there.

I stated it's misleading, because there's a comment next _exec&_spawn stating "C run-time library".

This information is correct, but to a newbie, it could mislead he/she into believing it's part of the C/C++ standard.
That's why I mentioned it as a clarification, and not as a correction.

FYI: system is a function that works in Windows too....

[Andreas Masur]

I'm not referring to it being misleading because of what thread it's in. If that was the case, I would have mention the other functions listed there.

I was referring to this thread...changing the content of the FAQ does have nothing to do with the question asked in this thread in the first place.

I stated it's misleading, because there's a comment next _exec&_spawn stating "C run-time library".

Yes...however, every function starting with '_' or '__' usually isn't part of the standard anyway...

Nevertheless, I have added some comment to these, thus, everybody should be satisfied by now...

[Jim1981]

Here's a wrapper function that should be able to do what you want:

BOOL ExecuteAndWaitForCompletion ( LPCTSTR pszCmd)
{
	STARTUPINFO si;
	PROCESS_INFORMATION pi;
	
	ZeroMemory ( &si, sizeof ( STARTUPINFO));
	
	si.cb = sizeof ( STARTUPINFO);
	si.dwFlags = STARTF_USESHOWWINDOW;
	si.wShowWindow = SW_HIDE;
	
	bRes     =     CreateProcess ( NULL,
		pszCmd
		NULL,
		NULL,
		TRUE,
		NORMAL_PRIORITY_CLASS,
		GetEnvironmentStrings     (),
		NULL,
		&si,
		&pi
		);
	
	WaitForSingleObject (     pi.hProcess,     INFINITE);
	
	CloseHandle( pi.hProcess);
	CloseHandle( pi.hThread);
	
	return ( bRes);
}

This is great thanks, exactly what I need. *I still need the return value from the launched .exe's main function, but I can look into how to do that possibly from here, even if I have to add some client/server code.

Cheers.

Edit: *I see this was already explained by Andreas - GetExitCodeProcess(). Thank you too, Andreas.