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Message1. Segmentation Fault with Win XP.
#5030
Posted by: hailang_82 2004-08-26 15:06:13
I am using Mingw 3.3.1, Dev C++ 4.9.8.10. And using WxWidgets 2.5.2. Recompiled it to enable ODBC support.

I am trying to create a Frame that allows me to type in data and upon clicking on a button..  a dialog box will pop up giving what I had typed.

I had an acesss violation (segmentation fault) whenever I click on the button. After some debugging... I isolate the error to this line.

wxString t2;
   t2.Append(theText->GetLineText(0));

In addition, sometimes the program also cannot compile giving error like
cannot find -lopengl32-g3. It's only after trying to compile a few times can it actually compile. But it still crash upon clicking on the button.


The following is my header file. Is build on the default wxWindows template.

#ifndef __BASE_H
#define __BASE_H

class MainApp: public wxApp
{
  public:
      virtual bool OnInit();
};

class MainFrame: public wxFrame
{
  public:
      MainFrame(const wxString &title, const wxPoint &pos, const wxSize &size);
      void OnQuit(wxCommandEvent &event);
      void OnButtonSelect(wxCommandEvent &event);  
      void OnFileOpen(wxCommandEvent &event);
      void OnAbout(wxCommandEvent &event);
     
      wxTextCtrl *theText;
     
  private:
      DECLARE_EVENT_TABLE()
};

enum
{
   ID_MAINWIN_QUIT = wxID_HIGHEST+1,
   ID_MAINWIN_OnButtonSelect,
   ID_MAINWIN_OnFileOpen,
   ID_MAINWIN_OnAbout
};


#endif


this is the base.cpp

#include <wx/wxprec.h>
#ifndef WX_PRECOMP
   #include <wx/wx.h>
#endif

#include "base.h"
#include "wx/db.h"

static const wxChar * TITLE = _T("Basic -step 3. Responding to events");
static const wxChar * FILETYPES = _T("Text Files|*.txt|"
"C/C++ source files|*.cpp;*.cc;*.c|");


IMPLEMENT_APP(MainApp)

bool MainApp::OnInit()
{

 MainFrame *win = new MainFrame("Frame", wxPoint (100, 100),
 wxSize(450, 340));
 win->Show(TRUE);
 SetTopWindow(win);

   return TRUE;
}


BEGIN_EVENT_TABLE(MainFrame, wxFrame)

   EVT_MENU(ID_MAINWIN_QUIT, MainFrame::OnQuit)
   EVT_MENU(ID_MAINWIN_OnFileOpen, MainFrame::OnFileOpen)
   EVT_MENU(ID_MAINWIN_OnAbout, MainFrame::OnAbout)
   EVT_BUTTON(ID_MAINWIN_OnButtonSelect, MainFrame::OnButtonSelect)

END_EVENT_TABLE()


MainFrame::MainFrame(const wxString &title, const wxPoint &pos, const wxSize &size)
    : wxFrame((wxFrame *) NULL, -1, title, pos, size)
{

    
 wxMenu *FileMenu = new wxMenu;
 FileMenu->Append(ID_MAINWIN_OnFileOpen,"& Open File");
 FileMenu->Append(ID_MAINWIN_OnAbout,"& About");
 FileMenu->AppendSeparator(); // a line that seperate items into logical group
 FileMenu->Append(ID_MAINWIN_QUIT, "&Quit");
 
 
 wxMenuBar *MenuBar = new wxMenuBar;
 MenuBar->Append(FileMenu, "&File");
 SetMenuBar(MenuBar); //???

 CreateStatusBar(2);
 SetStatusText("Welcome!");
 
wxTextCtrl *Dcontrol = new wxTextCtrl(this,-1,"Enter your query here",wxPoint(225,20),wxSize(200,20),0,wxDefaultValidator, "Frame");
wxStaticText * dytext = new wxStaticText(this,-1,"Type your query=>", wxPoint(20,20),wxSize(80,80),0,"Frame");
wxButton * dybutton = new wxButton(this,ID_MAINWIN_OnButtonSelect,"Send",wxPoint(100,100),wxSize(-1,-1),0,wxDefaultValidator,"Frame");

}

void MainFrame::OnButtonSelect(wxCommandEvent& event)
{
    wxString t2;
   t2.Append(theText->GetLineText(0)); //problem!!!!
  wxMessageDialog aboutDialog( this, t2, "About Queries", wxOK | wxCANCEL);
  aboutDialog.ShowModal();
 
}

void MainFrame::OnFileOpen(wxCommandEvent & WXUNUSED(event))
{
//  theText->LoadFile("data.txt");
    wxFileDialog * openFileDialog = new wxFileDialog(this,"Open File","","",FILETYPES,wxOPEN,wxDefaultPosition);
   
 /*   if (openFileDialog->ShowModal() == wxID_OK)
    {
        SetCurrentFilename(openFileDialog->GetFilename());
        theText->LoadFuke(openFileDialog->GetFilename());
        SetStatusText(GetCurrentFilename(),0);
        SetStatusText(openFileDialog->GetDirectory(),1);
    } */
}       
   
void MainFrame::OnAbout(wxCommandEvent & WXUNUSED(event))
{
    wxString t = TITLE;
    t.append( _T("\nDB 2001"));
    wxMessageDialog aboutDialog(this, t,"trying", wxOK|wxCANCEL);
    aboutDialog.ShowModal();
}

void MainFrame::OnQuit(wxCommandEvent & WXUNUSED(event))
{
    Close(TRUE);
}

Message2. Re: Segmentation Fault with Win XP.
#5031
Posted by: hailang_82 2004-08-26 15:41:09
HAHA.

Syntax error.

manage to run it successfully.
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