#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <winsock.h>
#include <io.h>

char *buffer = NULL;
char string[900];

float Zahl[100];
int i=0;
int Zeichen=0;
float Ergebnis;
char Zwischen[100];



HWND        hButton1;
HWND        hButton2;
HWND        hButton3;
HWND        hButton4;
HWND        hButton5;


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

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
    HWND     hWnd;
    MSG      msg;
    WNDCLASS wc;
    
    
    WNDCLASSEX  WindowClass;             // Die Fensterklasse
        

    const char szAppName[] = "Rechner";

   wc.style          = CS_HREDRAW | CS_VREDRAW;
    
    wc.cbClsExtra     = 0;
    wc.cbWndExtra     = 0;
    wc.hInstance      = hInstance;
    wc.hIcon          = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor        = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground  = GetSysColorBrush(COLOR_3DFACE);
    wc.lpszMenuName   = NULL;
    wc.lpfnWndProc    = WndProc;
    wc.lpszClassName  = szAppName;

    RegisterClass(&wc);

    hWnd = CreateWindow( szAppName,
                         "Taschenrechner",
                         WS_OVERLAPPEDWINDOW| WS_VISIBLE,
                         200,
                         200,
                         300,
                         200,
                         NULL,
                         NULL,
                         hInstance,
                         NULL );

    ShowWindow(hWnd, iCmdShow);
    UpdateWindow(hWnd);
  
  hButton1 = CreateWindow("BUTTON", "+",
                       WS_VISIBLE | WS_CHILD, 20, 50, 30, 30,
                       hWnd, NULL, hInstance, NULL);
        if(!hButton1) return FALSE;
  hButton2 = CreateWindow("BUTTON", "-",
                       WS_VISIBLE | WS_CHILD, 60, 50, 30, 30,
                       hWnd, NULL, hInstance, NULL);
        if(!hButton1) return FALSE;
  hButton3= CreateWindow("BUTTON", "*",
                       WS_VISIBLE | WS_CHILD, 100, 50, 30, 30,
                       hWnd, NULL, hInstance, NULL);
        if(!hButton1) return FALSE;
  hButton4 = CreateWindow("BUTTON", "/",
                       WS_VISIBLE | WS_CHILD, 140, 50, 30, 30,
                       hWnd, NULL, hInstance, NULL);
        if(!hButton1) return FALSE;
  hButton5 = CreateWindow("BUTTON", "=",
                       WS_VISIBLE | WS_CHILD, 180, 50, 30, 30,
                       hWnd, NULL, hInstance, NULL);
        if(!hButton1) return FALSE;
        
        
    SendMessage(hButton1, WM_SETFONT, (WPARAM)GetStockObject(DEFAULT_GUI_FONT), TRUE);
    SendMessage(hButton2, WM_SETFONT, (WPARAM)GetStockObject(DEFAULT_GUI_FONT), TRUE);
    SendMessage(hButton3, WM_SETFONT, (WPARAM)GetStockObject(DEFAULT_GUI_FONT), TRUE);
    SendMessage(hButton4, WM_SETFONT, (WPARAM)GetStockObject(DEFAULT_GUI_FONT), TRUE);
    SendMessage(hButton5, WM_SETFONT, (WPARAM)GetStockObject(DEFAULT_GUI_FONT), TRUE);
    
    while(GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
        static HWND hEdit;
        static HWND hText5;
        static HWND hText6;
        static HWND hTextf;

    switch(message)
    {
    case WM_CREATE:
        {
            hEdit = CreateWindowEx(WS_EX_CLIENTEDGE,
                                   "edit",
                                   buffer,    // <- das ist der Inhalt der Editfelds
                                   WS_CHILD | WS_VISIBLE,
                                   20, 20, 200, 20,
                                   hWnd,
                                   NULL,
                                   ((LPCREATESTRUCT) lParam) -> hInstance,
                                   NULL);

            free(buffer);
            
            
        SendMessage(hEdit, WM_SETFONT, (WPARAM)GetStockObject(DEFAULT_GUI_FONT), TRUE);
                
        return 0;

            
        }
        
    case WM_COMMAND:
                    {        // Ein Button wurde gedrückt, welcher?
                        if(lParam == (LPARAM)hButton1)        // +
                        {
                               int iLength;
            
                               iLength = GetWindowTextLength(hEdit);
                               buffer = malloc(iLength);
                               GetWindowText(hEdit, buffer, iLength+1);
                               strcpy(string,buffer);
                               sscanf(string,"%f",&Zahl[i]);
                               Zeichen=1;
                               i++;
                               SendMessage(hEdit, WM_SETTEXT, 0,(LPARAM)"");
                               SetFocus(hEdit);
                               free(buffer);
                         }
                         if(lParam == (LPARAM)hButton2)        // -
                        {
                               int iLength;
            
                               iLength = GetWindowTextLength(hEdit);
                               buffer = malloc(iLength);
                               GetWindowText(hEdit, buffer, iLength+1);
                               strcpy(string,buffer);
                               sscanf(string,"%f",&Zahl[i]);
                               Zeichen=2;
                               i++;
                               SendMessage(hEdit, WM_SETTEXT, 0,(LPARAM)"");
                               SetFocus(hEdit);
                               free(buffer);
                         } 
                         if(lParam == (LPARAM)hButton3)        // *
                        {
                               int iLength;
            
                               iLength = GetWindowTextLength(hEdit);
                               buffer = malloc(iLength);
                               GetWindowText(hEdit, buffer, iLength+1);
                               strcpy(string,buffer);
                               sscanf(string,"%f",&Zahl[i]);
                               Zeichen=3;
                               i++;
                               SendMessage(hEdit, WM_SETTEXT, 0,(LPARAM)"");
                               SetFocus(hEdit);
                               free(buffer);
                         }
                         if(lParam == (LPARAM)hButton4)        // /
                        {
                               int iLength;
            
                               iLength = GetWindowTextLength(hEdit);
                               buffer = malloc(iLength);
                               GetWindowText(hEdit, buffer, iLength+1);
                               strcpy(string,buffer);
                               sscanf(string,"%f",&Zahl[i]);
                               Zeichen=4;
                               i++;
                               SendMessage(hEdit, WM_SETTEXT, 0,(LPARAM)"");
                               SetFocus(hEdit);
                               free(buffer);
                         }
                         if(lParam == (LPARAM)hButton5)        // =
                        {
                              int iLength;
            
                              iLength = GetWindowTextLength(hEdit);
                              buffer = malloc(iLength);
                              GetWindowText(hEdit, buffer, iLength+1);
                              strcpy(string,buffer);
                              sscanf(string,"%f",&Zahl[i]);
                              i++;
                              SendMessage(hEdit, WM_SETTEXT, 0,(LPARAM)"");
            
                              free(buffer);
                              
                              if(Zeichen==1)
                              {
                                            Ergebnis = Zahl[i-2]+Zahl[i-1];
                              }
                              if(Zeichen==2)
                              {
                                            Ergebnis = Zahl[i-2]-Zahl[i-1];
                              }
                              if(Zeichen==3)
                              {
                                            Ergebnis = Zahl[i-2]*Zahl[i-1];
                              }
                              if(Zeichen==4)
                              {
                                            Ergebnis = Zahl[i-2]/Zahl[i-1];
                              }
                              sprintf(Zwischen,"%g",Ergebnis);
                              SendMessage(hEdit, WM_SETTEXT, 0,(LPARAM)Zwischen);
                              SetFocus(hEdit);
                              i=0;
                              Zeichen=0; 
                               
                         }
                      }    
                        break;
                        
    case WM_CLOSE:
        {
            DestroyWindow(hWnd);
            return 0;
        }
    case WM_DESTROY:
        {
            PostQuitMessage(0);
            return 0;
        }
    }
    return DefWindowProc(hWnd, message, wParam, lParam);
}