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Win API/How to use button

LacViet (82)
Hi guys. This is my first attempt at Win API. I am trying to mess with some of the sourcecode provided here at this site. And I am desperately in need of assistance. What I want to do is when I press a button. The button change a text. I trieded, and fail miserably, some help would be great. :)

I just wanted to try something simple to begin with. Is that when I press the button
: ID_BUTTON, or "calculate". The text in static_label. Would change to something else. It be great if someone can fix and point me to the right direction. TY. This is my code so far. I didn't get any errors--so I suppose there is a logic error somewhere. :( 

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#include "windows.h"

enum { ID_LABEL = 1,ID_IMAGE,ID_EDIT,ID_LIST,ID_BUTTON,ID_COMBO, ID_BUTTON2 };
LRESULT CALLBACK WinProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam); 

HINSTANCE g_hInst;
TCHAR	szAppName[]	= TEXT("SDI Frame");
TCHAR	szWinClass[]	= TEXT("WIN_CLASS");
HWND static_label;
HWND edit;
HWND button;

int WINAPI WinMain(HINSTANCE hInstance, 
		HINSTANCE hPrevInstance,
		PSTR lpCmdLine,
		int nCmdShow){
						
	MSG			msg; 
	WNDCLASS	wc;	
	HWND		hwnd; 
	g_hInst = hInstance;
	
	wc.cbClsExtra		= 0; 
	wc.cbWndExtra		= 0; 
	wc.hbrBackground	= (HBRUSH)(COLOR_WINDOW+1); 
	wc.hCursor			= LoadCursor(NULL, IDC_ARROW); 
	wc.hIcon			= LoadIcon(NULL, IDI_APPLICATION); 
	wc.hInstance		= hInstance; 
	wc.lpfnWndProc		= WinProc; 
	wc.lpszClassName	= szWinClass; 
	wc.lpszMenuName		= NULL; 
	wc.style			= CS_HREDRAW | CS_VREDRAW; 
 
 	if( !RegisterClass(&wc)) 
	{
		MessageBox(NULL, TEXT("Error registering class"), TEXT("ERROR"), MB_OK);
		return 0;
	}

	hwnd = CreateWindow(szWinClass,
						szAppName, 
						WS_OVERLAPPEDWINDOW, 
						CW_USEDEFAULT, 
						CW_USEDEFAULT, 
						300, 
						400, 
						(HWND) NULL, 
						(HMENU) NULL, 
						(HINSTANCE) hInstance, 
						(void *) NULL); 

	ShowWindow(hwnd, nCmdShow); 
	UpdateWindow(hwnd);	

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

LRESULT CALLBACK WinProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam){
	PAINTSTRUCT	ps;
	HDC			hdc;
	switch(msg){
	case WM_CREATE:
		static_label = CreateWindow("Static",
"Please Enter A Number",WS_CHILD | WS_VISIBLE,40,15,200,25,hwnd,0,g_hInst,0);	
		edit = CreateWindow("Edit", NULL
, WS_BORDER | NULL | WS_CHILD | WS_VISIBLE | NULL | NULL ,40,45,200,20,hwnd,(HMENU) NULL,g_hInst,0);
		button = CreateWindow("Button","Calculate",
BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE ,140,70,100,25,hwnd,(HMENU)ID_BUTTON,g_hInst,0);	
		case WM_PAINT: 
		hdc = BeginPaint(hwnd, &ps);
		EndPaint(hwnd, &ps);
		return 0;
	case ID_BUTTON:
		{
		// code
		SendMessage(static_label,LB_ADDSTRING,255,(LPARAM)(LPCSTR)"You clicked the button");
		ShowWindow(static_label,SW_SHOW);
		}
					break;	
	case WM_DESTROY: 
		PostQuitMessage(0);
		break; // pass to DefWindowProc(...) as well
	case WM_CLOSE:
		DestroyWindow(hwnd);
        break;
	}return DefWindowProc(hwnd, msg, wParam, lParam);}
guestgulkan (2942)
Problem here:
IIRC - Commands for childwindows (and menu options) are not sent as top level messages like this :
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switch (msg)
{
case ID_BUTTON:
{
    // code
    SendMessage(static_label,LB_ADDSTRING,255,(LPARAM)(LPCSTR)"You clicked the button");
    ShowWindow(static_label,SW_SHOW);
    }
break;


They are sent in the wParam part of the WM_COMMAND message.

Static windows don't do messages - so we will need to change that piece of code.

(ps You need a break statement for the WM_CREATE case)

Last edited on
guestgulkan (2942)
So in light of what I've said above - change your code to look like this
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		case WM_PAINT: 
		hdc = BeginPaint(hwnd, &ps);
		EndPaint(hwnd, &ps);
		return 0;
        case WM_COMMAND: //Command from Child windows and menus are under this message
            switch(wParam) //the ID is is wParam
            {
                case ID_BUTTON: //check for our button ID
                {
                    // Static labels dont do messages
                    //we can set the text directly though
                    SetWindowText(static_label,"You clicked the button");
                    break;
                }
            }
        break;
Nandor (83)
you can try this:
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BOOL keys[256];//global Variable
//...
case WM_KEYDOWN:
keys[wParam]=truel
case WM_KEYUP:
keys[wParam]=false;
//in the while loop in WINMAIN:
if(keys[/*coresponding key id,like VK_KEYDOWN,VK_ESCAPE or 'W','S'*/])
//do something
guestgulkan (2942)
Nandor what are you talking about?

The original request was that when a user clicked a pushbutton (Not a key on the keyboard!), he wanted to change the text of a label.

Maybe you replied to the wrong post.

Nandor (83)
oh,sorry......it's my fault
LacViet (82)
Thx A lot Guys. Now what if I wanted to do something else with the text, window. Basically what I wanted to do is build a calculator that look like the one that came with window. But a lot of this is not making anysense to me. I tried messing with all the window fx such as...SendMessage...etc. This the problem I have:

1. How do I get the number to stack-up to each other: EX. When I press button 1, the second press doesn't replace the first 1. So that I can enter multi-digits number. etc.

2. How do I get the text to align to the left?

3. How do I copy, or retrieve the text from the "edit" box, so I can utilizes it in a function, or class?

Any help is greatly appreciated guys. Thank you. 



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#include "windows.h"

enum { ID_LABEL = 1,ID_IMAGE,ID_EDIT,ID_LIST,ID_BUTTON1,ID_COMBO,ID_BUTTON2,ID_BUTTON0,
ID_BUTTON3,ID_BUTTON4,ID_BUTTON5,ID_BUTTON6,ID_BUTTON7,ID_BUTTON8,ID_BUTTON9, 
ID_BUTTONPLUS, ID_BUTTONMINUS, ID_BUTTONTIME, ID_BUTTONDIVIDE, ID_BUTTONEQUAL};
LRESULT CALLBACK WinProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam); 

HINSTANCE g_hInst;
TCHAR	szAppName[]	= TEXT("Calculator");
TCHAR	szWinClass[]	= TEXT("WIN_CLASS");

HWND static_label;
HWND edit;
HWND list; 
//number
HWND button0; 
HWND button1;
HWND button2;
HWND button3;
HWND button4;
HWND button5;
HWND button6;
HWND button7;
HWND button8;
HWND button9;
//operation
HWND buttonPlus; 
HWND buttonMinus;
HWND buttonTime;
HWND buttonDivide; 
HWND buttonEqual; 

int WINAPI WinMain(HINSTANCE hInstance, 
		HINSTANCE hPrevInstance,
		PSTR lpCmdLine,
		int nCmdShow){
						
	MSG			msg; 
	WNDCLASS	wc;	
	HWND		hwnd; 
	g_hInst = hInstance;
	
	wc.cbClsExtra		= 0; 
	wc.cbWndExtra		= 0; 
	wc.hbrBackground	= (HBRUSH)(COLOR_WINDOW+1); 
	wc.hCursor			= LoadCursor(NULL, IDC_ARROW); 
	wc.hIcon			= LoadIcon(NULL, IDI_APPLICATION); 
	wc.hInstance		= hInstance; 
	wc.lpfnWndProc		= WinProc; 
	wc.lpszClassName	= szWinClass; 
	wc.lpszMenuName		= NULL; 
	wc.style			= CS_HREDRAW | CS_VREDRAW; 
 
 	if( !RegisterClass(&wc)) 
	{
		MessageBox(NULL, TEXT("Error registering class"), TEXT("ERROR"), MB_OK);
		return 0;
	}

	hwnd = CreateWindow(szWinClass,
						szAppName, 
						WS_OVERLAPPEDWINDOW, 
						CW_USEDEFAULT, 
						CW_USEDEFAULT, 
						300, 
						400, 
						(HWND) NULL, 
						(HMENU) NULL, 
						(HINSTANCE) hInstance, 
						(void *) NULL); 

	ShowWindow(hwnd, nCmdShow); 
	UpdateWindow(hwnd);	

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

LRESULT CALLBACK WinProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam){
	PAINTSTRUCT	ps;
	HDC			hdc;
	
	switch(msg){
		case WM_CREATE:
			static_label = CreateWindow("Static","Please Enter A Number",WS_CHILD | WS_VISIBLE,35,15,175,25,hwnd,0,g_hInst,0);	
			edit = CreateWindow("Edit", NULL,WS_BORDER | NULL | WS_CHILD | WS_VISIBLE | NULL | NULL ,35,45,175,20,hwnd,(HMENU)ID_EDIT,g_hInst,0);
			
			button0 = CreateWindow("Button","0",BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE ,80,220,35,35,hwnd,(HMENU)ID_BUTTON0,g_hInst,0);	
			button1 = CreateWindow("Button","1",BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE ,35,170,35,35,hwnd,(HMENU)ID_BUTTON1,g_hInst,0);	
			button2 = CreateWindow("Button","2",BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE ,80,170,35,35,hwnd,(HMENU)ID_BUTTON2,g_hInst,0);	
			button3 = CreateWindow("Button","3",BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE ,125,170,35,35,hwnd,(HMENU)ID_BUTTON3,g_hInst,0);	
			button4 = CreateWindow("Button","4",BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE ,35,120,35,35,hwnd,(HMENU)ID_BUTTON4,g_hInst,0);	
			button5 = CreateWindow("Button","5",BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE ,80,120,35,35,hwnd,(HMENU)ID_BUTTON5,g_hInst,0);	
			button6 = CreateWindow("Button","6",BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE ,125,120,35,35,hwnd,(HMENU)ID_BUTTON6,g_hInst,0);	
			button7 = CreateWindow("Button","7",BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE ,35,70,35,35,hwnd,(HMENU)ID_BUTTON7,g_hInst,0);	
			button8 = CreateWindow("Button","8",BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE ,80,70,35,35,hwnd,(HMENU)ID_BUTTON8,g_hInst,0);	
			button9 = CreateWindow("Button","9",BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE ,125,70,35,35,hwnd,(HMENU)ID_BUTTON9,g_hInst,0);	
			
			buttonDivide = CreateWindow("Button","/",BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE ,170,70,35,35,hwnd,(HMENU)ID_BUTTONDIVIDE,g_hInst,0);	
			buttonTime = CreateWindow("Button","*",BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE ,170,120,35,35,hwnd,(HMENU)ID_BUTTONTIME,g_hInst,0);	
			buttonMinus = CreateWindow("Button","-",BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE ,170,170,35,35,hwnd,(HMENU)ID_BUTTONMINUS,g_hInst,0);	
			buttonPlus = CreateWindow("Button","+",BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE ,170,220,35,35,hwnd,(HMENU)ID_BUTTONPLUS,g_hInst,0);	
			buttonEqual = CreateWindow("Button","=",BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE ,125,220,35,35,hwnd,(HMENU)ID_BUTTONEQUAL,g_hInst,0);
			
		case WM_PAINT: 
			hdc = BeginPaint(hwnd, &ps);
			EndPaint(hwnd, &ps);
			return 0;
		case WM_COMMAND: //Command from Child windows and menus are under this message
            switch(wParam) //the ID is wParam
            {
                case ID_BUTTON0: //check for our button ID
					{
					// Static labels dont do messages
                    //we can set the text directly though
						
						SetWindowText(edit,"0");
						//SetWindowText(edit,"0");
						break;
					}
					
				case ID_BUTTON1:
					{
						SetWindowText(edit,"1");
						break;
					}
					
				case ID_BUTTON2:
					{
						SetWindowText(edit,"2");
						break;
					}
				
				case ID_BUTTON3:
					{
						SetWindowText(edit,"3");
						break;
					}
				
				case ID_BUTTON4:
					{
						SetWindowText(edit,"4");
						break;
					}
				
				case ID_BUTTON5:
					{
						SetWindowText(edit,"5");
						break;
					}
				
				case ID_BUTTON6:
					{
						SetWindowText(edit,"6");
						break;
					}
				                
				case ID_BUTTON7:
					{
						SetWindowText(edit,"7");
						break;
					}
				                
				case ID_BUTTON8:
					{
						SetWindowText(edit,"8");
						break;
					}
				
				case ID_BUTTON9: 
					{
						SetWindowText(edit,"9");
						break;
					}
					
				case ID_BUTTONPLUS: 
					{
						SetWindowText(edit,"+"); 
						break;
					}
				
				case ID_BUTTONMINUS: 
					{
						SetWindowText(edit,"-");
						break;
					}
				
				case ID_BUTTONTIME: 
					{
						SetWindowText(edit,"*");
						break;
					}
				
				case ID_BUTTONDIVIDE: 
					{
						SetWindowText(edit,"/");
						break;
					}
				case ID_BUTTONEQUAL:
					{
						SetWindowText(edit,"="); 
						break; 
					}
            }//switch. 
			break;
		case WM_DESTROY: 
			PostQuitMessage(0);
			break; // pass to DefWindowProc(...) as well
		case WM_CLOSE:
			DestroyWindow(hwnd);
			break;
	}return DefWindowProc(hwnd, msg, wParam, lParam);}
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