System() vs CreateProcess() vs ShellExecute()

Question

0.00/5 (No votes)

See more:

Here's one for everyone, I'm running a batch file within my main c++ program. From what I understand is that the batch becomes a child that might hangup the main program untill it completes. Now which method should I use that would allow the main program to continue along it's merry way while the batch is processing. Also the main program might and probably will create new child instances while the first child is running! Any thoughts welcome! This is Windows.

Posted 26-Sep-11 6:25am

Member 7766180

Updated 26-Sep-11 6:27am

v3

Add a Solution

Comments

mbue 26-Sep-11 12:57pm

"hangup the main program untill it completes" who told you that? ShellExecute is completely ansync. You can obtain a process handle to wait for, if you use ShellExecuteEx.
Regards.

Member 7766180 26-Sep-11 13:03pm

I'm going by what I read here. Am I misinterputing?
http://faq.cprogramming.com/cgi-bin/smartfaq.cgi?answer=1044654269&id=1043284392

mbue 26-Sep-11 14:06pm

Nice ;). ShellExecute is definitely async. And the others have flags to control the execution (i.e. P_WAIT or P_NOWAIT). Hope that helps.
Regards.

Member 7766180 26-Sep-11 14:44pm

Thank you. I will use ShellExecute.

Chuck O'Toole 26-Sep-11 14:06pm

in Unix / Linux, system() is a blocking call until the task completes. The Windows RTL implementation of the Unix call does the same thing. Native Windows calls (ShellExecute, ...) are asynch. He's talking about the Unix call.

mbue 26-Sep-11 14:28pm

Beg your pardon, but take a look at the headline and the link the op posted above.

Chuck O'Toole 26-Sep-11 15:20pm

Did that, both that, your point is? The entire first half of the article referenced to use fork(), spawn(), system(), etc. All Unix calls. Windows calls are described in the 2nd half. One of the downsides mentioned under the description of system() is that it returns after the the command is completed. The OP said that that he read that it might hangup the main program. You jumped on him for that. I pointed out to you that his reading was true if he was talking about the system() Unix call. Now you're jumping on me saying that I should read the headline and the link. Take your own advice and read for comprehension.

mbue 26-Sep-11 17:09pm

Take
* this
* this
* this
* and this
and now tell me a reason to assume the op is talking about unix calls!
I jump on nobody - im not a rolling cat.
Perhaps the op should decide first what os he/her want to use.
Regards.

Member 7766180 26-Sep-11 17:21pm

thanks mbue. you have it right. At the end of my question it says "windows" at te end of the link, it shows "window" solutions as well. I don't know where unix came from! ps, I did not feel jumped on by you! I have been jumped on in this forum but not by you!

Chuck O'Toole 26-Sep-11 22:44pm

Regarless of whether it's windows or not, the definiton of the unix function "system()" is to wait for the command to complete. When you use this function on windows, and it does work on windows, it is implemented exactly the same to be unix compatible therefore it does wait for the command to complete which is what you were concerned about.

Member 7766180 27-Sep-11 2:32am

Yeah, you are right. I just tried it and the main program hangs untill the bat is completed. My fear of fears. So is it ShellExecute()? and if so, do I need the error checking? And if not, how do I write it without (Prefered). Thank you.

mbue 27-Sep-11 16:46pm

Its always a good idea to have any kind of error handling. A simple message box to notify the user what happens when an error occures.
Regards.

Member 7766180 27-Sep-11 17:21pm

Please put your suggestion in solution so that I can give you credit and close this thread. Thank You.

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

mbue · Accepted Answer · 2011-09-27T15:03:00

Ok you want a suggestion:
1. Use ShellExecute to start another program from inside yours with asynchronous behauviour. This can be a 32- or 64- executable.
2. If you want to wait for the execution is finished, you should use ShellExecuteEx set the flag SEE_MASK_NOCLOSEPROCESS so you will get a valid process handle you can wait for with WaitForSingleObject.
3. You must not let your program wait until execution is finnished, you can set a timer by SetTimer and examine the ready state of the program youve started.
4. Its always a good idea to check the error state of the execution, perhaps to show the user whats going wrong (file not found, not an executable and so on). Simplest way is to display a MessageBox. Therefore you can use the FormatMessage function to obtain a human readable error text.
Regards and good luck.