Question

// diskbin.cpp : main project file.

#include "stdafx.h"
#include <windows.h>
#include <iostream>
#include <fstream>
#include <conio.h>
#include <stdio.h>
#include <sys/stat.h>

using namespace std;

int main( int argc, char *argv[] )
{
  //code

  if(stat("key.pc.db", &filek) ==0 )
      sizek=filek.st_size;
  if(stat("seek.pc.db", &files) ==0 )
      sizes=files.st_size;

  sizek=sizek/sizeof(int);
  sizes=sizes/sizeof(int);
  int i,min,max,mid;
  int *s=new int[sizes];
  int *hit=new int[sizes];

  //code
}

When I run this program in Visual Studio 2008, I am not getting any error but when I run the cmd opens and then closes followed by a pop up window which says:
“An unhandled exception of type ‘System.AccessViolationException’ occurred in diskbin.exe
Additional information: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.” What could be the issue? Have I not allocated s and hit properly?

Thanks!

Answer 1

It’s crashing because you’re using uninitialized variables:

  int       sizes, sizek;
  struct stat files, filek;
  ofstream ofs;

  if(stat("key.pc.db", &filek) ==0 )
      sizek=filek.st_size;
  if(stat("seek.pc.db", &files) ==0 )
      sizes=files.st_size;

  sizek=sizek/sizeof(int);
  sizes=sizes/sizeof(int);

if stat() fails, you use an uninitialized sizek.
Depending on the uninitialized memory, your next statement will crash:

int *s=new int[sizes];

because sizes can be negative or a very large number and the new will fail.

Check the error returned by stat(), although it’s possible the file key.pc.db is not found, causing the function to fail.