Win GUI App started from Console => print to console impossible?

this is not yet another "I need a console in my GUI app" that has been discussed quite frequently. My situation differs from that.

I have a Windows GUI application, that is run from a command line. Now if you pass wrong parameters to this application, I do not want a popup to appear stating the possible switches, but I want that printed into the console that spawned my process.

I got that far that I can print into the console (call to AttachConsole(...) for parent process) but the problem is my application is not "blocking". As soon as I start it, the command prompt returns, and all output is written into this window (see attached image for illustration).

I played around a bit, created a console app, ran it, and see there, it "blocks", the prompt only re-a开发者_StackOverflowppears after the app has terminated. Switching my GUI app to /SUBSYSTEM:Console causes strange errors (MSVCRTD.lib(crtexe.obj) : error LNK2019: nonresolved external Symbol "_main" in function "___tmainCRTStartup".)

I have seen the pipe approach with an ".exe" and a ".com" file approach from MSDEV but I find it horrible. Is there a way to solve this prettier?

This is not behaviour that you can change by modifying your application (aside from re-labelling it as already discussed). The command interpreter looks at the subsystem that an executable is labelled with, and decides whether to wait for the application to terminate accordingly. If the executable is labelled as having a GUI, then the command interpreter doesn't wait for it to terminate.

In some command interpreters this is configurable. In JP Software's TCC/LE, for example, one can configure the command interpreter to always wait for applications to terminate, even GUI ones. In Microsoft's CMD, this is not configurable behaviour, however. The Microsoft answer is to use the START command with the /WAIT option.

Once again: This is not the behaviour of your application. There is, apart from relabelling as a TUI program, no programmatic way involving your code to change this.

Maybe write a console-based wrapper app that checks the parameters, prints the error message on bad parameters, and calls/starts up the actual program when the parameters are correct?