C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Catching output of system()          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Arvin Portlock Guest Posted: Fri Mar 05, 2004 4:02 pm    Post subject: Catching output of system() I've written a perl cgi script but it's too slow so I need to rewrite it in C++. The perl script passes parameters to a search engine on our local filesystem and processes the results (number of hits, etc.). I've never had to do anything like this in C++ before and I don't know where to start. So what is the equivalent in C++ to something like this? open (RESULTS, "srch -q $word |"); Which is the perl method of opening a handle on the output of a pipe. I imagine I'd like to use system() but there doesn't seem to be a way to capture the output of the call. Reading through similar messages in this group I get the impression this really can't be done. It seems like I need to pass the search results to the program through the operating system (the results are VERY large), i.e., through STDIN. This would be less convenient since I'd like to package everything up in one program. Is this true? Is there not a way to do this? Back to top Leor Zolman Guest Posted: Fri Mar 05, 2004 4:07 pm    Post subject: Re: Catching output of system() On Fri, 05 Mar 2004 08:02:13 -0800, Arvin Portlock <apollock11 (AT) hotmail (DOT) com> wrote: Quote: I've written a perl cgi script but it's too slow so I need to rewrite it in C++. The perl script passes parameters to a search engine on our local filesystem and processes the results (number of hits, etc.). I've never had to do anything like this in C++ before and I don't know where to start. So what is the equivalent in C++ to something like this? open (RESULTS, "srch -q $word |"); Which is the perl method of opening a handle on the output of a pipe. I imagine I'd like to use system() but there doesn't seem to be a way to capture the output of the call. Reading through similar messages in this group I get the impression this really can't be done. It seems like I need to pass the search results to the program through the operating system (the results are VERY large), i.e., through STDIN. This would be less convenient since I'd like to package everything up in one program. Is this true? Is there not a way to do this? This is pretty platform-specific. Let me just suggest you download my STLFilt package for MSVC (link down in my sig), and examine the source code file CL.CPP. In it, Thomas Becker crafted some code to do piping between Win32 processes (one of which just happens to be a Perl interpreter, actually...). This may give you a leg-up. Good luck, -leor Leor Zolman BD Software [email]leor (AT) bdsoft (DOT) com[/email] www.bdsoft.com -- On-Site Training in C/C++, Java, Perl & Unix C++ users: Download BD Software's free STL Error Message Decryptor at www.bdsoft.com/tools/stlfilt.html Back to top Gianni Mariani Guest Posted: Fri Mar 05, 2004 5:30 pm    Post subject: Re: Catching output of system() Arvin Portlock wrote: Quote: I've written a perl cgi script but it's too slow so I need to rewrite it in C++. The perl script passes parameters to a search engine on our local filesystem and processes the results (number of hits, etc.). I've never had to do anything like this in C++ before and I don't know where to start. So what is the equivalent in C++ to something like this? open (RESULTS, "srch -q $word |"); Which is the perl method of opening a handle on the output of a pipe. I imagine I'd like to use system() but there doesn't seem to be a way to capture the output of the call. Reading through similar messages in this group I get the impression this really can't be done. It seems like I need to pass the search results to the program through the operating system (the results are VERY large), i.e., through STDIN. This would be less convenient since I'd like to package everything up in one program. Is this true? Is there not a way to do this? There is no -standard- way of doing this. However, you can use popen which exists in many systems (_popen in win32). If you're using a Linux/Unix system then you can implement it as a pipe/fork call and not use the C stdio at all. Back to top Default User Guest Posted: Fri Mar 05, 2004 5:31 pm    Post subject: Re: Catching output of system() Arvin Portlock wrote: Quote: So what is the equivalent in C++ to something like this? open (RESULTS, "srch -q $word |"); Which is the perl method of opening a handle on the output of a pipe. There isn't one. You are into the platform-specific realm now. If on a UNIX type system, the popen() function may be what you need. Questions about that should be addressed to comp.unix.programmer. Otherwise, find a newsgroup dedicated to your platform and ask there. Quote: I imagine I'd like to use system() but there doesn't seem to be a way to capture the output of the call. That's correct. Brian Rodenborn Back to top Arvin Portlock Guest Posted: Sun Mar 07, 2004 8:34 pm    Post subject: Re: Catching output of system() Arvin Portlock wrote: Quote: I've written a perl cgi script but it's too slow so I need to rewrite it in C++. The perl script passes parameters to a search engine on our local filesystem and processes the results (number of hits, etc.). I've never had to do anything like this in C++ before and I don't know where to start. So what is the equivalent in C++ to something like this? open (RESULTS, "srch -q $word |"); Which is the perl method of opening a handle on the output of a pipe. I imagine I'd like to use system() but there doesn't seem to be a way to capture the output of the call. Reading through similar messages in this group I get the impression this really can't be done. It seems like I need to pass the search results to the program through the operating system (the results are VERY large), i.e., through STDIN. This would be less convenient since I'd like to package everything up in one program. Is this true? Is there not a way to do this? Thanks for the suggestions! I know how to do this now. 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