Calculator in a dialog box

[slim2hott]

Im creating a calculator in a dialog box
I have created all my headers and resource files with all my buttons and edits ready.
This is a part of my .rc file:

EDITTEXT        IDC_NUMBER,3,7,100,14,ES_NUMBER
EDITTEXT        IDC_NUMBER2,130,7,100,14,ES_NUMBER

I have made these so the user can input integers and then use them later on to multiply/add/takeaway etc, using a few buttons (like I have said below)

PUSHBUTTON      "&Multiply",IDC_MULTIPLY,150,47,50,14

Im using that as my multiply button.
Lets say i created a switch statement and a case: IDC_MULTIPLY
what would I need to do after? could i just make an integar out of IDC_NUMBER and IDC_NUMBER2 like int number and int number2 and then type number * number 2? If so, then how would I show the answer of the multiplication in a listbox, (i also have a listbox ready in the .rc file.

If you didn't quite understand my question, here it goes again; What do I need to do in the case: IDC_MULTIPLY to add two intergers together and then add them to a list box?

Thanks in advance :)

[Clinton Portis]

#include<windows.h>
#include<sstream>
#include<string>
using namespace std;

/*  Declare Windows procedure  */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);

/*  Make the class name into a global variable  */
char szClassName[ ] = "calculator";

int WINAPI WinMain (HINSTANCE hThisInstance,
                    HINSTANCE hPrevInstance,
                    LPSTR lpszArgument,
                    int nFunsterStil)

{
    HWND hwnd;               /* This is the handle for our window */
    MSG messages;            /* Here messages to the application are saved */
    WNDCLASSEX wincl;        /* Data structure for the windowclass */

    /* The Window structure */
    wincl.hInstance = hThisInstance;
    wincl.lpszClassName = szClassName;
    wincl.lpfnWndProc = WindowProcedure;      /* This function is called by windows */
    wincl.style = CS_DBLCLKS;                 /* Catch double-clicks */
    wincl.cbSize = sizeof (WNDCLASSEX);

    /* Use default icon and mouse-pointer */
    wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
    wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
    wincl.lpszMenuName = NULL;                 /* No menu */
    wincl.cbClsExtra = 0;                      /* No extra bytes after the window class */
    wincl.cbWndExtra = 0;                      /* structure or the window instance */
    /* Use Windows's default color as the background of the window */
    wincl.hbrBackground = (HBRUSH)(COLOR_BACKGROUND);

    /* Register the window class, and if it fails quit the program */
    if (!RegisterClassEx (&wincl))
        return 0;

    /* The class is registered, let's create the program*/
    hwnd = CreateWindowEx (
           0,                   /* Extended possibilites for variation */
           szClassName,         /* Classname */
           "calculator",       /* Title Text */
           WS_OVERLAPPEDWINDOW, /* default window */
           CW_USEDEFAULT,       /* Windows decides the position */
           CW_USEDEFAULT,       /* where the window ends up on the screen */
           257,                 /* The programs width */
           282,                 /* and height in pixels */
           HWND_DESKTOP,        /* The window is a child-window to desktop */
           NULL,                /* No menu */
           hThisInstance,       /* Program Instance handler */
           NULL                 /* No Window Creation data */
           );

    /* Make the window visible on the screen */
    ShowWindow (hwnd, nFunsterStil);

    /* Run the message loop. It will run until GetMessage() returns 0 */
    while (GetMessage (&messages, NULL, 0, 0))
    {
        /* Translate virtual-key messages into character messages */
        TranslateMessage(&messages);
        /* Send message to WindowProcedure */
        DispatchMessage(&messages);
    }

    /* The program return-value is 0 - The value that PostQuitMessage() gave */
    return messages.wParam;
}


class Calculator
{
 public:
       
        //Constructor
        Calculator();
        //WinProc Functions
        void command(WPARAM, LPARAM);        
        void create(HWND);
        int  destroy();
        //Other
        void perform_previous_op(); 
 
 private:  
             
        char   prev_op;
        double dSubtotal, 
               dTotal;
        string strSubtotal;               
        bool   bDecimal, 
               bClear;         
        HWND   hNumbers[10], 
               hOperators[4], 
               hDecimal, 
               hClear, 
               hDisplay, 
               hEquals;     
        
};

enum keypad
{
     ID_Button_0,
     ID_Button_1, ID_Button_2, ID_Button_3,
     ID_Button_4, ID_Button_5, ID_Button_6,
     ID_Button_7, ID_Button_8, ID_Button_9, 
     ID_Decimal,  ID_Button_EQU,     
     ID_Button_ADD,   ID_Button_SUB, 
     ID_Button_MULT,  ID_Button_DIV,
     ID_Button_CLEAR, ID_Static 
};

/*  This function is called by the Windows function DispatchMessage()  */

LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{   
   
   static Calculator MyCalc;
               
    switch (message)                  /* handle the messages */
    {        
        case WM_CREATE:   MyCalc.create(hwnd);               break;   
        case WM_COMMAND:  MyCalc.command(wParam, lParam);    break;
        case WM_DESTROY:  MyCalc.destroy();                  break;        
            
        default:                      /* for messages that we don't deal with */
            return DefWindowProc (hwnd, message, wParam, lParam);
    }

    return 0;
}




/////////////////////////////////////////
///////// Function Definitions //////////
/////////////////////////////////////////

Calculator::Calculator()
{
    dTotal = 0.0;
    dSubtotal = 0.0;  
    bDecimal = false;
    bClear = false;
    prev_op = 0;
}

void Calculator::create(HWND hwnd)
{

   int index = 1;
   TCHAR *numbers[]   = {"1","2","3","4","5","6","7","8","9"};
   
   for(int y=150; y>49; y-=50)
   for(int x=0;  x<101; x+=50)    
   {                 
      hNumbers[index] = CreateWindow("BUTTON", numbers[index-1], 
                            WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON,
                            x, y, 50, 50, hwnd, (HMENU)index,
                            (HINSTANCE)GetWindowLong(hwnd, GWL_HINSTANCE), NULL);  
                            index++;                    
   }
   
   index = 0;
   TCHAR *operators[] = {"+","-","*","/"};
   
   int x  = 150, y = 0;
   int ID = ID_Button_ADD;      
   
   for(int i=0; i<4; i++)
   {
      hOperators[i]   = CreateWindow("BUTTON", operators[i], 
                            WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON,
                            x, y+=50, 50, 50, hwnd, (HMENU)ID++,
                            (HINSTANCE)GetWindowLong(hwnd, GWL_HINSTANCE), NULL);
   }     

   
   hNumbers[0]   = CreateWindow("BUTTON", "0", WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON,
                           0, 200, 100, 50, hwnd, (HMENU)ID_Button_0,
                           (HINSTANCE)GetWindowLong(hwnd, GWL_HINSTANCE), NULL); 
                          
   hDecimal      = CreateWindow("BUTTON", ".", WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON,
                           100, 200, 50, 50, hwnd, (HMENU)ID_Decimal,
                           (HINSTANCE)GetWindowLong(hwnd, GWL_HINSTANCE), NULL);
                          
   hClear        = CreateWindow("BUTTON", "Clear", WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON,
                           200, 50, 50, 100, hwnd, (HMENU)ID_Button_CLEAR,
                           (HINSTANCE)GetWindowLong(hwnd, GWL_HINSTANCE), NULL);  
                          
   hDisplay      = CreateWindow("STATIC", NULL , WS_CHILD|WS_VISIBLE|WS_BORDER|ES_RIGHT,
                           5, 10, 188, 20, hwnd, (HMENU)ID_Static, 
                           (HINSTANCE)GetWindowLong(hwnd, GWL_HINSTANCE), NULL);
   
   hEquals       = CreateWindow("BUTTON", "=", WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON,
                           200, 150, 50, 100, hwnd, (HMENU)ID_Button_EQU,
                           (HINSTANCE)GetWindowLong(hwnd, GWL_HINSTANCE), NULL);  
}


void Calculator::command(WPARAM wParam, LPARAM lParam)
{   
    
    WORD msg = LOWORD(wParam);
    TCHAR *numbers[]   = {"0","1","2","3","4","5","6","7","8","9","."};
     
     if(HIWORD(wParam) == BN_CLICKED)
     {     
        //Numbers 1 thru 9
        if(msg >= ID_Button_1 && msg <= ID_Button_9)
        {    
             if(bClear)
             {
                strSubtotal.clear();
                SetWindowText(hDisplay, strSubtotal.c_str());
                bClear = false;
             }
                           
             strSubtotal += numbers[msg];
             SetWindowText(hDisplay, strSubtotal.c_str());      
        }
        
        //Number 0 (special case to eliminate leading zeros)
        else if(msg == ID_Button_0 && strSubtotal.size() && !bClear)
        {                           
             strSubtotal += "0";
             SetWindowText(hDisplay, strSubtotal.c_str());
        }
        
        //Decimal (special case to eliminate multiple decimals)
        else if(msg == ID_Decimal && !bDecimal)
        {
             if(bClear)
             {
                strSubtotal.clear();
                SetWindowText(hDisplay, strSubtotal.c_str());
                bClear = false;
             }
             
             bDecimal = true;
             strSubtotal += ".";
             SetWindowText(hDisplay, strSubtotal.c_str());
        } 
        
        //Operators +, -, *, /
        else if(msg >= ID_Button_ADD && msg <= ID_Button_DIV)
        {
             bClear = true;
             bDecimal = false;
             
             if(prev_op)
                                     
                perform_previous_op();
                 
             else
             {   
                istringstream atod(strSubtotal);
                atod >> dTotal; 
             }                       
                 
             switch(msg)
             {
                case ID_Button_ADD:  prev_op = '+';   break;
                case ID_Button_SUB:  prev_op = '-';   break;
                case ID_Button_MULT: prev_op = '*';   break;
                case ID_Button_DIV:  prev_op = '/';   break;
             }
                           
             SetWindowText(hDisplay, strSubtotal.c_str());
        }
        
        //Equals
        else if(msg == ID_Button_EQU)
        {
             if(prev_op)
             
                perform_previous_op();

             bClear = true;             
             SetWindowText(hDisplay, strSubtotal.c_str());
        }             
        
        //Clear
        else if(msg == ID_Button_CLEAR)
        {
             prev_op   = 0;
             dSubtotal = 0.0;
             dTotal    = 0.0;
             bClear    = false;
             bDecimal  = false;            
             strSubtotal.clear();
             SetWindowText(hDisplay, strSubtotal.c_str());
        }     
        
    }
}    
          

void Calculator::perform_previous_op()
{    
   istringstream atod(strSubtotal);
   atod >> dSubtotal;
   
   switch(prev_op)
   {
      case '+':  dTotal += dSubtotal;   break;
      case '-':  dTotal -= dSubtotal;   break;
      case '*':  dTotal *= dSubtotal;   break;
      case '/':  dTotal /= dSubtotal;   break;   
   }
   
   ostringstream dtoa;
   dtoa << dTotal;
   strSubtotal = dtoa.str();     
}
                           
  
int Calculator::destroy() 
{
     PostQuitMessage(0);
     return 0;
}

[William Hemsworth]

Code

What's this? You just supplied an entire program when all he wanted was help on one case.

[slim2hott]

Thank you very much clinton, although I did not want to go this far, this should help me out a lot. But one question, can I not do this the way I asked or does it have to be in classes?

Anyway Thanks again, I will use this to form my own.

What's this? You just supplied an entire program when all he wanted was help on one case.

I was a bit surprised :O