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Using dialogs in console apps

, 23 May 2000
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Learn how to display a message box from a console application.

Introduction

Traditionally, the world has been divided into two kinds of apps, and ne'er the twain shall meet: Console applications and GUI applications. (Actually, if you write a console app that talks to a scanner, and a GUI app that talks to a scanner, they both meet the TWAIN...)

Strictly speaking, this separation has not been true. A console app can presumably create a message loop and pop up windows; a GUI app can create and attach a console. But these are considered major pieces of effort.

A popular reason GUI apps seem to want to create consoles is to have a logging window to which debug output can be written. I solved this problem years ago with a technology that has evolved into a fairly sophisticated set of MFC classes, my Logging ListBox class.

However, last week a client contacted me. He needed the ability to handle a MessageBox from a console app, and I had everything working with one little, but showstopper, glitch: I couldn't find any API that gave me a handle to the window in which the console app was running.

So I did the obvious thing: I posted the question on the microsoft.public.vc.mfc newsgroup where I hang out. Sure enough, David Lowndes replied within minutes with the solution, which I have incorporated into the answer below. Thanks, and a Tip Of The Flounder Fin to David.

David's suggestion was to use SetConsoleTitle to set a window title for the window, then use FindWindow to find it. In order to guarantee the name is unique, he also suggested using a GUID (my favorite technique) for the window name, since that guarantees that no other window will have that name!

HWND FindConsoleHandle()
{
   static LPCTSTR temptitle = _T("{98C1C303-2A9E-11d4-9FF5-006067718D04}");
   TCHAR title[512];
   if(GetConsoleTitle(title, sizeof(title)/sizeof(TCHAR)) == 0)
      return NULL;
   SetConsoleTitle(temptitle);
   HWND wnd = FindWindow(NULL, temptitle);
   SetConsoleTitle(title);
   return wnd;
}

To invoke the MessageBox, just use the HWND returned from this function as the HWND for the parent window.

For example, I am now able to execute the following in a plain-vanilla console app:

int response = MessageBox( FindConsoleHandle(), 
                           _T("File read error, continue?"), 
                           _T("File Error"), 
                           MB_ICONERROR | MB_YESNO);

Be sure to replace the GUID above with a GUID of your own that you get from GUIDGEN; otherwise you lose the desired uniqueness.

This should work equally well for operations like standard dialogs such as File Open, File Save, and even custom dialogs of your own. Note that it won't work for modeless dialogs, because they don't have their own message pump.


The views expressed in these essays are those of the author, and in no way represent, nor are they endorsed by, Microsoft.

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Joseph M. Newcomer

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Comments and Discussions

 
GeneralThere is always an easier way Pinmemberbdawson@newcorp.com22-Feb-06 8:26 
General? What about the other way around PinmemberSynetech4-Dec-03 18:18 
GeneralLet me know too, please! PinsussAnonymous3-Apr-04 2:44 
GeneralRe: Let me know too, please! Pinmemberbaker_tony3-Apr-04 2:46 
Bah, I didn't log in when I posted that message!
email is "baker_tony AT hotmail.com"
GeneralRe: ? What about the other way around PinmemberJoseph M. Newcomer3-Apr-04 7:13 
GeneralRe: ? What about the other way around PinmemberWasteland76-May-04 21:24 
GeneralRe: ? What about the other way around Pinmembercowsonfire22-Feb-06 1:42 
GeneralBeeter way to get HWND of parent PinmemberMLoibl16-Feb-01 8:00 
Generala missing thing PinmemberMLoibl16-Feb-01 22:58 
GeneralRe: Beeter way to get HWND of parent PinmemberLim Bio Liong8-Jan-02 20:07 
GeneralRe: Beeter way to get HWND of parent PinmemberWasteland76-May-04 21:20 
GeneralYou don't need all this code Pinsusslandshark7-Jun-00 3:55 
GeneralRe: You don't need all this code PinsussGene18-Jul-00 7:34 
GeneralEast is east... PinsussRavi Bhavnani6-Jun-00 9:18 
GeneralRe: dialogs in console apps PinsussGisle Vanem24-May-00 22:05 

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