Problems in obtain the Input value of Fl_Float_Input class

Newhunter · #1 20-Jan-2009, 05:45

Hi! I am with a problem, I am unable to obtain the value of a Fl_Float_Input, the object appears correctly in the window but when I try to catch the value of the object of the class Fl_Float_Input it seems that the pointer is with problems. I am using Microsoft Visual Studio 2005 and the problem that appears is "Unhandled exception at 0x1022faec (msvcr80d.dll) in Project.exe: 0xC0000005: Access violation reading location 0xfeeefeee." and the program breaks.

He is the .h and the .cpp of this class:

CPP / C++ / C Code:

#ifndef WINDOWDOSADORCLASS_H
#define WINDOWDOSADORCLASS_H

#include "MainWindow.h"

class WindowDosadorClass {
public:
	Fl_Window* Dosador();
private:
	Fl_Window* Window_Dosador;
	Fl_Float_Input *Input_Alcool;
    Fl_Float_Input *Input_Catalizador;
	Fl_Return_Button* Bt_ok;
	static void Button_OK_Dosador_cb(Fl_Widget* w, void* v);
    static void Button_Cancelar_Dosador_cb(Fl_Widget* w, void* v);
	void CriarDosador_UI();  
	double alc;
        double cat;
};

#endif

CPP / C++ / C Code:

#include "WindowDosadorClass.h"
#include <iostream>
#include <stdlib.h>


Fl_Window* WindowDosadorClass::Dosador(){
	{ Window_Dosador = new Fl_Window(250,200,340, 240, "Entrada para o Dosador");
    Window_Dosador->box(FL_GTK_UP_BOX);
    Window_Dosador->user_data((void*)(this));
     Input_Alcool = new Fl_Float_Input(150, 61, 113, 25, "Quantidade de alcool: ");
      Input_Alcool->box(FL_GTK_DOWN_BOX);
	   // Fl_Input* Input_Alcool

     Input_Catalizador = new Fl_Float_Input(180, 99, 119, 26, "Quantidade de catalizador: ");
      Input_Catalizador->box(FL_GTK_DOWN_BOX);
	   // Fl_Input* Input_Catalizador

     Bt_ok = new Fl_Return_Button(75, 175, 100, 30, "OK");
     Bt_ok->box(FL_GTK_UP_BOX);
     Bt_ok->callback(Button_OK_Dosador_cb,(void*)this);
     // Fl_Return_Button* o

    { Fl_Button* o = new Fl_Button(205, 175, 90, 30, "Cancelar");
      o->box(FL_GTK_UP_BOX);
	  o->callback(Button_Cancelar_Dosador_cb,Window_Dosador);
    } // Fl_Button* o

    { new Fl_Box(50, 10, 230, 45, "Defina as entradas para o Dosador");
    } // Fl_Box* o
	Window_Dosador->end();
	Window_Dosador->show();
	
  } // Fl_Window* Window_Dosador
  return Window_Dosador;
}


void WindowDosadorClass::Button_Cancelar_Dosador_cb(Fl_Widget* w, void* v){
	w->~Fl_Widget();
	((Fl_Window*)v)->~Fl_Window();
}
void WindowDosadorClass::CriarDosador_UI(){ //Here is the problem, all this code does not works!!
	Input_Alcool->clear_changed();
	Input_Catalizador->clear_changed();
	alc =  atof(Input_Alcool->value());  //Here the program breaks,seems like Bad Ptr 
	cat =  atof(Input_Catalizador->value());
	CriarDosador(alc,cat); //method of another class that receive the values
}
void WindowDosadorClass::Button_OK_Dosador_cb(Fl_Widget* w, void* v){
	w->~Fl_Widget();
	((WindowDosadorClass*)v)->Window_Dosador->~Fl_Window();
	((WindowDosadorClass*)v)->CriarDosador_UI(); //Call the method to 
//acess the objects Input_Alcool and Input_Catalizador of Fl_Float_Input //class
	
}

Hope someone can help me understand this stuff!!

Thanks!!

colagor · #2 20-Feb-2009, 16:35

i think those access violations indicate, that your code is trying to write to memory location that it has not claimed. hence it is "violating" your operating systems memory management. if it succeeded, that would be a "buffer overrun" where by it could (possibly) inject your own data or worse code into another program, or your operating system's reserved memory.

an example would be this:

CPP / C++ / C Code:

int main(void)
    {
     char dodgyArray[2];
     dodgyArray[] = "possibly malicious code"
    return 1;
    }

this is a buffer overrun because i declared the array to be two characters long and then tried to write to it much more than that.

so as far as your code is concerned, try commenting out those callbacks and see if it still does it.
I'm too much of noob so say whats wrong just by looking at it, but i got the same problem with callbacks before.

colagor · #3 20-Feb-2009, 17:21

sorry that code would just give an assignment error, this code would possibly give you your access violation

CPP / C++ / C Code:

int main(void)
    {
    int dodgyArray[2];
    dodgyArray[5] = 1;
    return 1;
    }

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Problems in obtain the Input value of Fl_Float_Input class

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Re: Problems in obtain the Input value of Fl_Float_Input class