Access Violation

Question

Greetings everyone, going to need some help in clearing this exception.

I get the following when debugging my compiled program in Microsoft Visual C++ 6.0:

Loaded 'ntdll.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\kernel32.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\tsappcmp.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\msvcrt.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\advapi32.dll', no matching symbolic information found.
Loaded 'C:\WINDOWS\system32\rpcrt4.dll', no matching symbolic information found.
First-chance exception in SA.exe: 0xC0000005: Access Violation.

Here are the relevant screenshots from the debugger.

Showing ostream.h:

http://img237.imageshack.us/my.php?image=accessviolation.png'>http://img237.imageshack.us/img237/1116/accessviolation.th.png' border='0'/>

Showing main.ccp:

http://img509.imageshack.us/my.php?image=accessviolation2.png'>http://img509.imageshack.us/img509/3619/accessviolation2.th.png' border='0'/>

I've tried to scour my code for null pointers and have also tried to ignore the exception with no luck. Here are the three main components of my script:

main.ccp

#include <iostream>

#include "SA.h" 

using namespace std; // For the use of text generation in application


int main() 
{
    SimAnneal Go;

    cout << "Quadratic Function" << endl
      << "Solving method: Simulated Annealing" << endl;

    cout << "\nSelect desired Initial Temperature:" << endl
      << "> ";
    cin >> Go.T_initial;

    cout << "\nSelect desired number of Temperature Iterations:" << endl
      << "> ";
    cin >> Go.N_max;

    cout << "\nSelect desired number of step Iterations:" << endl
      << "> ";
    cin >> Go.N_step;

    cout << "\nSelect desired Absolute Temperature:" << endl
      << "> ";
    cin >> Go.T_abs;

    Go.LoadCities();

    Go.Initialize();

    Go.SA();

    system ("PAUSE");

    return 0;
}

SA.h

    #ifndef SA_H
    #define SA_H


class SimAnneal {

        double S_order [15];  
        double S_trial [15];  

        int SwapNum1;
        int SwapNum2;

        double CityArray [15][15];

        double E_initial;
        double E_current;

        double T;

        void Metropolis (double, int, int);
        void Next_State (double, int);
        double Schedule (double, int);
        double ObjFunction (double CityOrder []);

        void EquateArray ();
        void OrderInt ();
        void OrderTrial ();
        void OrderList (double array[]);

        void WriteResults (double, double, double, double, double);

      public:
        int N_step;
        int N_max; 
        double T_initial;
        double T_abs;

        void SA ();
        void Initialize ();
        void LoadCities ();
    };


    double Random_Number_Generator(double nHigh, double nLow);


#endif

SA.cpp

#include <math.h>
#include <iostream>
#include <fstream>    
#include <iterator>
#include <iomanip>
#include <time.h>     
#include <cstdlib>    

#include "SA.h"

using namespace std;


void SimAnneal::SA() 
{
    T = T_initial;
    E_current = E_initial;


        for ( int N_temperatures = 1 ; N_temperatures <= N_max ; N_temperatures++ )
        {
      Metropolis(T, N_step, N_temperatures);
            T = Schedule(T, N_temperatures);

     if (T <= T_abs)
      break;
        }

    cout << "\nResults:" << endl
    << "Distance> " << E_current << endl
    << "Temperature> " << T << endl;

    OrderList(S_order);
}

void SimAnneal::Metropolis(double T_current, int N_Steps, int N_temperatures)
{
    for ( int i=1; i <= N_step; i++ )   
     Next_State(T_current, N_temperatures);  
}

void SimAnneal::Next_State (double T_current, int i) 
{
    OrderTrial();

    double EXP = 2.718281828;

    double E_t = ObjFunction(S_trial);
    double E_c = ObjFunction(S_order);

    double deltaE = E_t - E_c;        
        if ( deltaE <= 0 )
        {    
     EquateArray();
     E_current = E_t;
    }
        else
        {
        double R = Random_Number_Generator(1,0);
     double Ratio = 1-(float)i/(float)N_max;   
     double ctrl_pram = pow(EXP, (-deltaE / T_current));

            if (R < ctrl_pram*Ratio)      
            {   
      EquateArray();
      E_current = E_t;
     }
     else 
      E_current = E_c;
    }
}

double SimAnneal::Schedule (double Temp, int i) 
{
    double CoolingRate = 0.9999;

    return Temp *= CoolingRate; 
}

double SimAnneal::ObjFunction (double CityOrder []) 
{
    int a, b;

    double distance = 0;

    for (int i = 0; i < 15 - 1; i++)
    {
     a =  CityOrder [i];
     b =  CityOrder [i + 1];

     distance += CityArray [a][b];
    }

    return distance;
}

void SimAnneal::Initialize () 
{
    int a, b;

    double distance = 0;

    OrderInt();

    for (int i = 0; i < 15 -1; i++)
    {
     a =  S_order [i];
     b =  S_order [i + 1];

     distance += CityArray [a][b];
    }

    E_initial = distance;
}

void SimAnneal::EquateArray () 
{
    for (int i = 0; i < 15; i++)
    {
     S_order [i] = S_trial [i];
    }
}

void SimAnneal::OrderInt () 
{
    for (int i = 0; i <15; i++)
    {
     S_order [i] = i;
    }
}

void SimAnneal::OrderTrial () 
{
    for (int i = 0; i < 15; i++)
    {
     S_trial [i] = S_order [i];
    }

    SwapNum1 = (int)Random_Number_Generator(15, 0);   
    SwapNum2 = (int)Random_Number_Generator(15, 0);

    for (int n = 0; n <= 100000; n++)      
    {
     SwapNum2 = (int)Random_Number_Generator(15, 0); 

     if ( SwapNum1 != SwapNum2 )
      break;
    }

    S_trial [SwapNum1] = S_order [SwapNum2];
    S_trial [SwapNum2] = S_order [SwapNum1];
}

void SimAnneal::OrderList (double array[]) 
{
    cout << "Array List : " << endl;
    for (int i = 0; i < 15; i++)
    {
     cout << " > " << array[i] << endl;
    }

    cout << "End of array" << endl;
}

void SimAnneal::LoadCities () 
{
    int x, y;

    for (y = 0; y < 15; y++)     
    {    
     for (x = 0; x < 15; x++)   
     {      
      if (x == y)
      { CityArray[x][y] = 0.0; 
      }
      else if (x != y)
      { CityArray[x][y] = Random_Number_Generator(7, 1); 
      }
     }  
    }  

    for (y = 0; y < 15; y++) 
    {    
     for (x = 0; x < 15; x++) 
     {      
      if (y > x)
       CityArray[y][x] = CityArray[x][y];
     }  
    }  
}

double Random_Number_Generator(double nHigh, double nLow)
{
    double fr = ((rand() % ((int)nHigh*1000 - (int)nLow*1000 + 1)) + nLow) / 1000;

    return fr;
}

Any Assistance would be much appriciated. I'm all out of ideas myself.

Answer 1

It doesn't really look like you are doing anything too fatal in your code that I can see, have you tried removing lines of code?

Answer 2

a = S_order [i];
b = S_order [i + 1];
distance += CityArray [a][b]; <--- This looks suspicious. When i = 14, b = 15...clearly outside the range... my 2 cents

Answer 3

try this:

http://bytes.com/groups/net-vc/535224-whats-first-chance-exception-how-do-i-fix

But I think the answer is what someone else said - the distance = line

Answer 4

The code you posted wouldn't even compile:

1)

cin >> Go.Write;

There's no such variable in the SimAnneal class.

2)

Go.SA(Go.Write)

Your SA method doesn't accept any parameters.

Another thing is, why don't you run your project in debug mode directly in VC++ 6.0? The VS on the screenshots is clearly 200*X*.

According to the screenshots, you're crashing on the line:

cout << "Quadratic Function" << endl
     << "Solving method: Simulated Annealing" << endl;

Which doesn't make much sense, unless your output stream is mutilated in some way. Have you tried watching the console before the crash occurs?

Answer 5

for (int i = 0; i < 15; i++)
{
    S_trial [i] = S_order [i];
}

// ....
for (int i = 0; i <15; i++)
{
    S_order [i] = i;
}

Both loops are going too high. Change them to 14 instead of 15.

Answer 6

you can always put try { } catch(...) { } blocks around code and compile with /EHa

to identify the problem areas