also ich habe folgendes Programm:

#include <windows.h>
#include <windef.h>
#include <winuser.h>

#define edit1     1
#define button1   2
#define button2   3

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM);

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
     static char szAppName[] = "Name" ;
     HWND        hwnd ;
     MSG         msg ;
     WNDCLASSEX  wndclass ;

     wndclass.cbSize        = sizeof (wndclass) ;
     wndclass.style         = CS_HREDRAW | CS_VREDRAW ;
     wndclass.lpfnWndProc   = WndProc ;
     wndclass.cbClsExtra    = 0 ;
     wndclass.cbWndExtra    = 0 ;
     wndclass.hInstance     = hInstance ;
     wndclass.hIcon         = LoadIcon (NULL, IDI_APPLICATION) ;
     wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW) ;
     wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
     wndclass.lpszMenuName  = NULL ;
     wndclass.lpszClassName = szAppName ;
     wndclass.hIconSm       = LoadIcon (NULL, IDI_APPLICATION) ;

     RegisterClassEx (&wndclass) ;

     hwnd = CreateWindow (szAppName, "WinAPI", WS_OVERLAPPEDWINDOW,
			  CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,
			  NULL, NULL, hInstance, NULL) ;	

     ShowWindow (hwnd, iCmdShow) ;
     UpdateWindow (hwnd) ;

     while (GetMessage (&msg, NULL, 0, 0))
          {
          TranslateMessage (&msg) ;
          DispatchMessage (&msg) ;
          }
     return msg.wParam ;
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
{
        static HWND hwndedit1, hwndbutton1, hwndbutton2; 
        LRESULT a = 1, b = 2;
        switch (iMsg)
        {
               case WM_CREATE :
			   hwndedit1 = CreateWindowEx(WS_EX_CLIENTEDGE ,"edit", NULL,WS_CHILD | WS_VISIBLE | ES_LEFT,
				        0, 0, 150, 20, hwnd, (HMENU) edit1,
				        ((LPCREATESTRUCT) lParam) -> hInstance, NULL) ;
	           SendMessage(hwndedit1, WM_SETFONT,(WPARAM)GetStockObject(DEFAULT_GUI_FONT),0);
	           SendMessage(hwndedit1, WM_SETTEXT, 0, (long)"1");

			   hwndbutton1 = CreateWindow ("button", "Bitte Klicken",
   	                     WS_CHILD | WS_VISIBLE | BS_PUSHBUTTON,
				         0, 40, 150, 30, hwnd, (HMENU) button1,
				         ((LPCREATESTRUCT) lParam) -> hInstance, NULL) ; //Button "=" bzw. Berechne
               SendMessage(hwndbutton1, WM_SETFONT,(WPARAM)GetStockObject(DEFAULT_GUI_FONT),0);

               hwndbutton2 = CreateWindow ("button", "Open MessageBox", 
                          WS_CHILD | WS_VISIBLE | BS_PUSHBUTTON | BS_VCENTER,
                          10, 100, 500, 30, hwnd, (HMENU) button2,
                          ((LPCREATESTRUCT) lParam) -> hInstance, NULL);
               SendMessage(hwndbutton2, WM_SETFONT,(WPARAM)GetStockObject(DEFAULT_GUI_FONT),0);

			   return 0 ;

		       case WM_COMMAND:
			   switch (HIWORD(wParam))//Aktionsauswahl
			   {
			          case BN_CLICKED://Button gedrückt ?
				      switch(LOWORD(wParam))//Welcher ?
				      {
                           case button1:
					       SendMessage(hwndedit1,WM_SETTEXT,0,(long)"Der Button wurde gedrückt");
					       break;

					       case button2:

                           if (SendMessage(hwndedit1, WM_GETTEXT, 0, 0) == (long)"1")                           
                           SendMessage (hwndedit1, WM_SETTEXT, 0, (long)"2");
                           else 
                           if (SendMessage(hwndedit1, WM_GETTEXT, 0, 0) == (long)"2")
                           SendMessage(hwndedit1, WM_SETTEXT, 0, (long)"1");
                           else
                           MessageBox(hwnd,"gvzgd","hbcfe",0);

                           break;
				       }
				       break;
			  }
			  return 0;

			  case WM_DESTROY :
				  PostQuitMessage (0) ;
				  return 0 ;
	 }
     return DefWindowProc (hwnd, iMsg, wParam, lParam) ;
}

Also, das Programm soll eigentlich Wenn man den unteren Button drückt die 1 in der Editbox zu einer 2 machen oder andersrum.

Ich denke der Fehler liegt hier drin:

if (SendMessage(hwndedit1, WM_GETTEXT, 0, 0) ==(long)"1") [/code]

aber ich hab keine ahnung wie ich ihn beheben kann.

Kann mir jemand helfen?

Schonmal danke im voraus!

Und jetzt funkt es sogar, vielen dank!

LRESULT CALLBACK WndProc (HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
{
        static HWND hwndedit1, hwndbutton1, hwndbutton2; 
        LRESULT a = 1, b = 2;
        int ilen;
        char puffer[10];
        switch (iMsg)
        {
               case WM_CREATE :
			   hwndedit1 = CreateWindowEx(WS_EX_CLIENTEDGE ,"edit", NULL,WS_CHILD | WS_VISIBLE | ES_LEFT,
				        0, 0, 150, 20, hwnd, (HMENU) edit1,
				        ((LPCREATESTRUCT) lParam) -> hInstance, NULL) ;
	           SendMessage(hwndedit1, WM_SETFONT,(WPARAM)GetStockObject(DEFAULT_GUI_FONT),0);

			   hwndbutton1 = CreateWindow ("button", "Bitte Klicken",
   	                     WS_CHILD | WS_VISIBLE | BS_PUSHBUTTON,
				         0, 40, 150, 30, hwnd, (HMENU) button1,
				         ((LPCREATESTRUCT) lParam) -> hInstance, NULL) ; //Button "=" bzw. Berechne
               SendMessage(hwndbutton1, WM_SETFONT,(WPARAM)GetStockObject(DEFAULT_GUI_FONT),0);

               hwndbutton2 = CreateWindow ("button", "Open MessageBox", 
                          WS_CHILD | WS_VISIBLE | BS_PUSHBUTTON | BS_VCENTER,
                          10, 100, 500, 30, hwnd, (HMENU) button2,
                          ((LPCREATESTRUCT) lParam) -> hInstance, NULL);
               SendMessage(hwndbutton2, WM_SETFONT,(WPARAM)GetStockObject(DEFAULT_GUI_FONT),0);
               SendMessage(hwndedit1, WM_SETTEXT, 0, (long)"1");       

			   return 0 ;

		       case WM_COMMAND:
			   switch (HIWORD(wParam))//Aktionsauswahl
			   {
			          case BN_CLICKED://Button gedrückt ?
				      switch(LOWORD(wParam))//Welcher ?
				      {
                           case button1:
					       SendMessage(hwndedit1,WM_SETTEXT,0,(long)"Der Button wurde gedrückt");
					       break;

					       case button2: 	           
                           ilen = SendMessage(hwndedit1,WM_GETTEXTLENGTH,0,0);
                           SendMessage(hwndedit1, WM_GETTEXT, ilen+1, (long)puffer);

                           if (puffer[0] == '1')                           
                           SendMessage (hwndedit1, WM_SETTEXT, 0, (long)"2");
                           else 
                           if (puffer[0] == '2')
                           SendMessage(hwndedit1, WM_SETTEXT, 0, (long)"1");
                           else
                           MessageBox(hwnd,"gvzgd","hbcfe",0);

                           break;
				       }
				       break;
			  }
			  return 0;

			  case WM_DESTROY :
				  PostQuitMessage (0) ;
				  return 0 ;
	 }
     return DefWindowProc (hwnd, iMsg, wParam, lParam) ;
}