Thread: Edit Box Question

After restarting my project (I fixed my memory leakage problems), I need some more help. Does anyone know how to clear the contents of a edit box when someone wants to start a new project?

Thanks in advance

You can use SendMessage() to send the WM_SETTEXT message to the editbox. Just set the text to "".

An application sends a WM_SETTEXT message to set the text of a window.

WM_SETTEXT
wParam = 0; // not used; must be zero
lParam = (LPARAM)(LPCTSTR)lpsz; // address of window-text string


Parameters

lpsz

Value of lParam. Points to a null-terminated string that is the window text.

Return Values

The return value is TRUE if the text is set. It is FALSE (for an edit control), LB_ERRSPACE (for a list box), or CB_ERRSPACE (for a combo box) if insufficient space is available to set the text in the edit control. It is CB_ERR if this message is sent to a combo box without an edit control.

- Sean

Originally posted by sean345
You can use SendMessage() to send the WM_SETTEXT message to the editbox. Just set the text to "".


- Sean

Thank you. I'll see what happens

Ok, I tried what you said (I think). Here's the code I did:

Code:

		case IDM_NEW:
			//MessageBox(hwnd, "Option not in", NULL, NULL);
			SendMessage(hwnd, WM_SETTEXT, 0, 0);
			break;

(IDM_NEW worked before [tested with a message box])....there's no errors, it just won't clear the edit box.

I think it should be:

Code:

SendMessage(hwnd, WM_SETTEXT, 0,(LPCTSTR)"");

- Sean

Originally posted by sean345
I think it should be:

Code:

SendMessage(hwnd, WM_SETTEXT, 0,(LPCTSTR)"");

- Sean

Code:

C:\Program Files\Microsoft Visual Studio\MyProjects\Window Code Test\Window Code Test.cpp(40) : error C2664: 'SendMessageA' : cannot convert parameter 4 from 'char *' to 'long'

Tried what you had above, and that's the error I get (anyone know why it says long?)

Because you are not sending the message to the right handle. You are just sending it to hwnd, your main window handle. You need to send the message to the editbox. like so:

Code:

SendMessage(GetDlgItem(hwnd,ID_OF_YOUR_EDITBOX)),WM_SETTEXT,0,(LPARM)"");

You got that error because the 4th parmater in SendMessage has to be cast to (LPARAM) not LPCTSTR

Originally posted by Dohojar
Because you are not sending the message to the right handle. You are just sending it to hwnd, your main window handle. You need to send the message to the editbox. like so:

Code:

SendMessage(GetDlgItem(hwnd,ID_OF_YOUR_EDITBOX)),WM_SETTEXT,0,(LPARM)"");

>>You got that error because the 4th parmater in SendMessage has to be cast to (LPARAM) not LPCTSTR

Ok, thanks. That worked. While I'm on the edit box deal, how would you resize the edit box when someone maximizes it (or hwo do you make it fullscreen by default).

>>After reading the SendMessage() on MSDN, I kinda thought that that is why<<

Originally posted by Quantrizi
how would you resize the edit box when someone maximizes it (or hwo do you make it fullscreen by default).

Handle WM_SIZE message of the parent window. The lParam has the client dimensions of the parent window packed into it which can be used, if required, to position and size your control. Use LOWORD and HIWORD macros on the lParam value to retrieve these values. I believe that a search of this board should have explicit examples of how to use this message handler in this way if you need them.

Originally posted by Ken Fitlike
Handle WM_SIZE message of the parent window. The lParam has the client dimensions of the parent window packed into it which can be used, if required, to position and size your control. Use LOWORD and HIWORD macros on the lParam value to retrieve these values. I believe that a search of this board should have explicit examples of how to do this if you need them.

Would that also resize the edit box also?

>>> or hwo do you make it fullscreen by default

You correct your design/UI so that it is not necessary.

Code:

case WM_SIZE:
  {
  WORD cx,cy;
  cx=LOWORD(lParam);  /*parent width*/
  cy=HIWORD(lParam);  /*parent height*/
  
  /*move edit so that it fills parent's client area*/
  /* hEdit is handle to your edit control*/
  MoveWindow(hEdit, 0, 0, cx, cy, TRUE);
  return 0;
  }

You could obviously alter the parameters to MoveWindow to adjust the size and position of your edit control. Some people prefer to use SetWindowPos instead of MoveWindow.

Originally posted by Ken Fitlike

Code:

case WM_SIZE:
  {
  WORD cx,cy;
  cx=LOWORD(lParam);  /*parent width*/
  cy=HIWORD(lParam);  /*parent height*/
  
  /*move edit so that it fills parent's client area*/
  /* hEdit is handle to your edit control*/
  MoveWindow(hEdit, 0, 0, cx, cy, TRUE);
  return 0;
  }

You could obviously alter the parameters to MoveWindow to adjust the size and position of your edit control. Some people prefer to use SetWindowPos instead of MoveWindow.

Ok, thank you. That works perfectly, except that when I do, my status bar is like duplicated (it resizes correctly, but it sticks a copy of itself where it was before resize until I move the cursor down there.

Also, if a user selects a button to insert something, I'd use WM_GETTEXT and WM_SETTEXT, wouldn't I (to add the text the user selected)?

>>my status bar is like duplicated (it resizes correctly, but it sticks a copy of itself where it was before resize until I move the cursor down there.<<

Then adjust the size/position of your edit control to take into consideration any other controls, including your status bar, that occupy the client area of the parent window. Use GetClientRect to get the dimensions of the statusbar control.

edit:
>> Also, if a user selects a button to insert something, I'd use WM_GETTEXT and WM_SETTEXT, wouldn't I (to add the text the user selected)?<<

Time to read up on edit controls.