Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

problem in delete in Debug mode

Posted on 2006-11-16
6
Medium Priority
?
243 Views
Last Modified: 2010-04-01
Hi experts,

I have a code, which generates an "invalid memory access" exception when I close my application. That is, I am getting exception when the destructor of my class is called.

In constructor, I am allocating (new) NO_OF_BUFFS amount of memory chunks. And in desctuctor, I am deleting these. I am not able to understand why I am getting exception everytime I delete.

**The exception occurs only in Debug mode, not it Release mode.**

I have also attached the code snippet for your reference:

Class Declaration:
----------------------
typedef unsigned char UINT8;
UINT8*      m_ppCBuffer[NO_OF_BUFFS];

Constructor:
----------------------
for(int i = 0; i < NO_OF_BUFFS;  i++)
{
      m_ppCBuffer[i] = new UINT8[BUFF_SIZE];
      if(!m_ppCBuffer[i])
      {
            MessageBox(NULL, TEXT("Not able to allocate enough memory"), NULL, NULL);
            break;
      }
      m_acBufferStatus[i] = READY_FOR_WRITE;
}

Desctructor:
----------------------
for(int i = 0;
i < NO_OF_BUFFS;
i++)
{
      if(m_ppCBuffer[i])
      {
            delete [] (m_ppCBuffer[i]);
            //delete (m_ppCBuffer[i]);
            m_ppCBuffer[i] = NULL;
      }
}

My doubt is, should I allocate memory for m_ppCBuffer also?

Thanks in advance,
Vikram_B.
0
Comment
Question by:Vikram_B
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
6 Comments
 
LVL 12

Expert Comment

by:rajeev_devin
ID: 17955259
>> In constructor, I am allocating (new) NO_OF_BUFFS amount of memory chunks. And in desctuctor, I am deleting
>> these. I am not able to understand why I am getting exception everytime I delete.
Somewhere in your code you are you are crossing the allocated size BUFF_SIZE.
0
 
LVL 12

Expert Comment

by:rajeev_devin
ID: 17955270
In general, when you deallocate an allocated memory,
and if any crash comes it indicates that you are crossing the boundary of allocated space.
Please check the other part of your code.

I hope it helps.
0
 

Author Comment

by:Vikram_B
ID: 17955304

> Somewhere in your code you are you are crossing the allocated size BUFF_SIZE

But, I am getting that error only when deleting (in the destructor).
0
Concerto Cloud for Software Providers & ISVs

Can Concerto Cloud Services help you focus on evolving your application offerings, while delivering the best cloud experience to your customers? From DevOps to revenue models and customer support, the answer is yes!

Learn how Concerto can help you.

 
LVL 12

Expert Comment

by:rajeev_devin
ID: 17962374
I think you didn't get my point.
Check this code.

class testClass
{
      char* m_str;

public:
      testClass() {
            m_str = new char[1]; // Allocating
      }

      ~testClass() {
            delete [] m_str; // Deallocating. Will crash here.
      }

      void crossBoundary() {
            m_str[1] = 10; // Here I am crossing boundary.
      }
};

int main()
{
      testClass t;
      t.crossBoundary();
      return (0);
}
0
 
LVL 12

Accepted Solution

by:
rajeev_devin earned 100 total points
ID: 17962385
You can clearly see from the above code.
>> m_str = new char[1]; // Allocating
Allocated 1 char space here.

>> m_str[1] = 10;
Assigning value in the 2nd char which I didn't allocate.

Hope that helps.
0
 
LVL 6

Expert Comment

by:SJT2003A
ID: 17966655
Simply remove the following line in your destructor.
Once after you delete the memory allocation, you can not assign a value though it is a NULL.

  m_ppCBuffer[i] = NULL;  // remove this line completely

Good luck :)
0

Featured Post

What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

  Included as part of the C++ Standard Template Library (STL) is a collection of generic containers. Each of these containers serves a different purpose and has different pros and cons. It is often difficult to decide which container to use and …
Go is an acronym of golang, is a programming language developed Google in 2007. Go is a new language that is mostly in the C family, with significant input from Pascal/Modula/Oberon family. Hence Go arisen as low-level language with fast compilation…
The goal of the tutorial is to teach the user how to use functions in C++. The video will cover how to define functions, how to call functions and how to create functions prototypes. Microsoft Visual C++ 2010 Express will be used as a text editor an…
The viewer will learn how to use the return statement in functions in C++. The video will also teach the user how to pass data to a function and have the function return data back for further processing.

704 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question