如何让 EnumWindows 列出所有窗口？

Question

I'm assuming, what I'm asking should actually be the default, but I'm experiencing some behavior I don't understand.

#include "stdafx.h"

using namespace std;

BOOL CALLBACK enumWindowsProc(
  __in  HWND hWnd,
  __in  LPARAM lParam
) {
  if( !::IsIconic( hWnd ) ) {
    return TRUE;
  }

  int length = ::GetWindowTextLength( hWnd );
  if( 0 == length ) return TRUE;

  TCHAR* buffer;
  buffer = new TCHAR[ length + 1 ];
  memset( buffer, 0, ( length + 1 ) * sizeof( TCHAR ) );
  
  GetWindowText( hWnd, buffer, length + 1 );
  tstring windowTitle = tstring( buffer );
  delete[] buffer;

  wcout << hWnd << TEXT( ": " ) << windowTitle << std::endl;

  return TRUE;
}

int _tmain( int argc, _TCHAR* argv[] ) {
  wcout << TEXT( "Enumerating Windows..." ) << endl;
  BOOL enumeratingWindowsSucceeded = ::EnumWindows( enumWindowsProc, NULL );
  cin.get();
  return 0;
}

If I invoke that code, it will list all minimized windows:

Now, I'm no longer interested in only the minimized windows, now I want all of them. So I remove the IsIconic check:

BOOL CALLBACK enumWindowsProc(
  __in  HWND hWnd,
  __in  LPARAM lParam
) {
  /*
  if( !::IsIconic( hWnd ) ) {
    return TRUE;
  }
  */

  int length = ::GetWindowTextLength( hWnd );
  if( 0 == length ) return TRUE;

  TCHAR* buffer;
  buffer = new TCHAR[ length + 1 ];
  memset( buffer, 0, ( length + 1 ) * sizeof( TCHAR ) );
  
  GetWindowText( hWnd, buffer, length + 1 );
  tstring windowTitle = tstring( buffer );
  delete[] buffer;

  wcout << hWnd << TEXT( ": " ) << windowTitle << std::endl;

  return TRUE;
}

Now I get all windows except the minimized ones (none of the previously listed window handles are listed this time):

For completeness, this is the stdafx.h :

#pragma once

#include "targetver.h"


#include <iostream>
#include <map>
#include <string>

namespace std {
  #if defined _UNICODE || defined UNICODE
    typedef wstring tstring;
  #else
    typedef string tstring;
  #endif
}

#include <stdio.h>
#include <tchar.h>
#include <Windows.h>
#include <psapi.h>

What am I doing wrong?

Answer 1

Well, wcout.flush() never works, however wcout.clear() fixes your code, at least for me.

wcout << hWnd << TEXT( ": " ) << windowTitle << std::endl;
wcout.clear();
return TRUE;

And I know that this question is already one year old, however it's never too late to answer.

Answer 2

Here is a callback function that lists all open windows:

#include <string>
#include <iostream>
#include <Windows.h>

static BOOL CALLBACK enumWindowCallback(HWND hWnd, LPARAM lparam) {
    int length = GetWindowTextLength(hWnd);
    char* buffer = new char[length + 1];
    GetWindowText(hWnd, buffer, length + 1);
    std::string windowTitle(buffer);

    // List visible windows with a non-empty title
    if (IsWindowVisible(hWnd) && length != 0) {
        std::cout << hWnd << ":  " << windowTitle << std::endl;
    }
    return TRUE;
}

int main() {
    std::cout << "Enmumerating windows..." << std::endl;
    EnumWindows(enumWindowCallback, NULL);
    std::cin.ignore();
    return 0;
}

If you want to check if the window is minimized, you can use IsIconic() .

See Also:

• Microsoft: EnumWindows function
• Stack Overflow: Getting a list of all open windows in c++ and storing them

Answer 3

It's (as I assumed) not a problem with EnumWindows at all. The problem is with the output stream.

While debugging, I noticed that enumWindowsProc is called just fine for every window, but that some iterations are simply not generating output.

For the time being, I switched to using _tprintf , but I don't understand what the problem with the original code is. Calling wcout.flush() had no desirable effect either.

Answer 4

Documentation of Windows (dunno its accuracy) says that EnumWindows only enumerates top level windows. If you wish to enumerate child windows, you need to use EnumChildWindows function where you have to pass handle of parent window