Thread: help finding a bug

Code:

#include <windows.h>
#include "resource.h"

char* revstr(char*);

BOOL CALLBACK DlgProc(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch(message)
    {
        case WM_INITDIALOG:
            return TRUE;
        break;

        case WM_COMMAND:
            switch(LOWORD(wParam))
            {
                case ID_INVERT:
                {
                    int length = GetWindowTextLength(GetDlgItem(hDlg, ID_TXT_NORMAL));
                    if(length > 0){
                        char* text;
                        char* reversed;

                        text = (char*)GlobalAlloc(GPTR, length + 1);
                        GetDlgItemText(hDlg, ID_TXT_NORMAL, text, length + 1);

                        reversed = revstr(text);

                        SetDlgItemText(hDlg, ID_TXT_NORMAL, reversed);
                        SendDlgItemMessage(hDlg, ID_TXT_NORMAL, WM_SETFOCUS, 0, 0);
                        SendDlgItemMessage(hDlg, ID_TXT_NORMAL, EM_SETSEL, 0, -1);
                        GlobalFree((HANDLE)text);
                    }

                    else
                        MessageBox(hDlg, "Digite alguma coisa...", "Aviso", MB_OK | MB_ICONWARNING);
                }
                return TRUE;

                case ID_COPY:
                {
                    int length = GetWindowTextLength(GetDlgItem(hDlg, ID_TXT_NORMAL));
                    if(length > 0)
                        SendDlgItemMessage(hDlg, ID_TXT_NORMAL, WM_CUT, 0, 0);

                    else
                        MessageBox(hDlg, "Não tem nada para ser copiado...", "Aviso", MB_OK | MB_ICONWARNING);
                }
                return TRUE;

                case ID_PASTE:
                    SendDlgItemMessage(hDlg, ID_TXT_INVERTED, WM_PASTE, 0, 0);
                return TRUE;

                case ID_TRANSLATE:
                {
                    int length = GetWindowTextLength(GetDlgItem(hDlg, ID_TXT_INVERTED));
                    if(length > 0){
                        char* text;
                        char* reversed;

                        reversed = (char*)GlobalAlloc(GPTR, length + 1);
                        GetDlgItemText(hDlg, ID_TXT_INVERTED, reversed, length + 1);

                        text = revstr(reversed);
                        SetDlgItemText(hDlg, ID_TXT_INVERTED, text);
                        GlobalFree((HANDLE)reversed);
                    }

                    else
                        MessageBox(hDlg, "Não há nada para traduzir...", "Aviso", MB_OK | MB_ICONWARNING);
                }
                return TRUE;
            }
        break;

        case WM_CLOSE:
            EndDialog(hDlg, 0);
        return TRUE;

        default:
            return FALSE;
    }
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
                   PSTR szCmdLine, int iCmdShow)
{
    return (int)DialogBox(hInstance, MAKEINTRESOURCE(ID_MAIN), NULL, DlgProc);
}

char* revstr(char* a)
{
  size_t temp, x, y = strlen(a) - 1;

  for ( x = 0; x < y; x++, y-- ){
    temp = a[x]; 
    a[x] = a[y]; 
    a[y] = temp;
  }

  return a;
}

If I type something in ID_TXT_NORMAL, click the ID_COPY button and paste what's on the clipboard to whatever program, when I click on the dialog box again I am not able to input text on ID_TXT_NORMAL without using that tab key on the keyboard. I noticed that this happens because the focus is still on the button I last clicked. Can you guys help me find the problem? Thanks.

Try using the SetFocus function to transfer focus back to the text control. Also, consider what will happen when a zero length string is passed to revstr.