Error Message when run program

When running my program I get an error message that says this:

Quote:

Debug Error!

HEAP CORRUPTION DETECTED: before Normal block(#1262858) at 0x268F3148.
CRT detected that the application wrote to memory before start of heap buffer.

What could this meen. Sometimes when running the program this error doesn´t come up and sometimes it does.

It is to much code to present here but what I do is to read .txt files into vectors and 2D vectors.
I know it perheps is difficult to know what it could depend on, but any idéas, guesses is welcome on this one.
I dont really dont know where to begin my search in the code.

If you are using an index in a vector or string that is invalid you might get something like that. Use at() instead of [] and you will get an exception that might help you identify the source of the problem.

Also, you should be able to debug your program and look at the call stack to see where in your code this corruption is occurring. Then you can post just that code and whatever is relevant to it so we can take a look.

sorry if asking but what is the "call stack". Is this something inside VC++ that creates when just debugging the program and not run it ?

Yes. When you run your program through the debugger (in VC++ that's F5 to Start or Run, not Ctrl-F5 or Execute), one of the windows that you can open is the Call Stack. When you get the error you mentioned or any other unhandled exception, VC++ will stop the program and you can view where it occurred and what the data is in the location that is being executed.

So try running it instead of executing it, then do whatever you need to do to get the error to occur. When it gives you the option you should break and then find the call stack window and look for code that you wrote and recognize. Then double click on that code and it should take you to about the place where the error is occurring.

Call stack is the sequence of functions in the order they called each other.
So if main calls A, which calls B, which calls C, there's a little window called "Call stack" in Visual Studio (when running the debugger) that shows how these functions called each other.
So you should be able to see where in what function the exception occurs.

And heap corruption means you wrote to some place in memory where you shouldn't have. You wrote beyond the end of your buffer.

I succeded to get an error while running the program with key "F5". When the error message came up, I choosed "Break".
The Errormessage was this:

Quote:

An unhandled exception of type ´System.AccessViolationException´
occured in Form1.exe

Additional information: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

Then I got a Break at line 141. I attach some lines before and after. Does this say anything meeningful. In the callstack window, It point to:
>Form1.exe!std::allocator<int>::deallocate(int* _Ptr = 0x25F7A298, unsigned int __unnamed001 = 200) Line 141 C++

Code:

132 template<class _Other> 133 allocator<_Ty>& operator=(const allocator<_Other>&) 134 { // assign from a related allocator (do nothing) 135 return (*this); 136 } 137 138 void deallocate(pointer _Ptr, size_type) 139 { // deallocate object at _Ptr, ignore size 140 ::operator delete(_Ptr); 141 } 142 143 pointer allocate(size_type _Count) 144 { // allocate array of _Count elements 145 return (_Allocate(_Count, (pointer)0)); 146 } 147 148 pointer allocate(size_type _Count, const void _FARQ *) 149 { // allocate array of _Count elements, ignore hint 150 return (allocate(_Count)); 151 }

So look in the call stack window and there should be something below that line that comes from your code. Double click on the line that is in your code.

Under the the line(141) that is the first line here. There is also these lines present under this line. Does this meen that there is something wrong with all of these lines ?

Code:

> Form1.exe!std::allocator<int>::deallocate(int* _Ptr = 0x25F7A298, unsigned int __unnamed001 = 200) Line 141 C++ Form1.exe!std::vector<int,std::allocator<int> >::_Tidy() Line 1139 C++ Form1.exe!std::vector<int,std::allocator<int> >::~vector<int,std::allocator<int> >() Line 559 + 0x9 bytes C++ Form1.exe!std::vector<int,std::allocator<int> >::`scalar deleting destructor' + 0x1e bytes Form1.exe!std::_Destroy<std::vector<int,std::allocator<int> > >(std::vector<int,std::allocator<int> >* _Ptr = 0x0D3648C0) Line 59 + 0xa bytes C++ Form1.exe!std::allocator<std::vector<int,std::allocator<int> > >::destroy(std::vector<int,std::allocator<int> >* _Ptr = 0x0D3648C0) Line 161 C++ Form1.exe!std::_Destroy_range<std::allocator<std::vector<int,std::allocator<int> > > >(std::vector<int,std::allocator<int> >* _First = 0x0D3648C0, std::vector<int,std::allocator<int> >* _Last = 0x0D4A84C0, std::allocator<std::vector<int,std::allocator<int> > >& _Al = {...}, std::_Nonscalar_ptr_iterator_tag __unnamed003 = {...}) Line 234 + 0xc bytes C++ Form1.exe!std::_Destroy_range<std::allocator<std::vector<int,std::allocator<int> > > >(std::vector<int,std::allocator<int> >* _First = 0x0D2C0040, std::vector<int,std::allocator<int> >* _Last = 0x0D4A84C0, std::allocator<std::vector<int,std::allocator<int> > >& _Al = {...}) Line 226 C++ Form1.exe!std::vector<std::vector<int,std::allocator<int> >,std::allocator<std::vector<int,std::allocator<int> > > >::_Destroy(std::vector<int,std::allocator<int> >* _First = 0x0D2C0040, std::vector<int,std::allocator<int> >* _Last = 0x0D4A84C0) Line 1124 + 0x10 bytes C++ Form1.exe!std::vector<std::vector<int,std::allocator<int> >,std::allocator<std::vector<int,std::allocator<int> > > >::_Tidy() Line 1137 C++ Form1.exe!std::vector<std::vector<int,std::allocator<int> >,std::allocator<std::vector<int,std::allocator<int> > > >::~vector<std::vector<int,std::allocator<int> >,std::allocator<std::vector<int,std::allocator<int> > > >() Line 559 + 0x9 bytes C++ Form1.exe!Form1::Form3::Optimize_Click(System::Object^ sender = 0x014edd44, System::EventArgs^ e = 0x0156c254) Line 4213 + 0x1a4 bytes C++

When doubleclicking all of these lines, it takes me to code I haven´t wrote. It is I beleive debugging code in any way.

The funny thing is that Form1 that it refer to here doesn´t do any calculation. This form Only open new forms, so on this form there is 7 buttoncontrols only. Not one calculation, vector, string, int or anything here.

That's the call stack. It means that each function is calling the function above it. The one on the bottom appears to be your code? Scroll down to the line that has the code you wrote and only double-click that line.

If you haven't written any of them, at least you should recognize some, like the bottom one, which references Form3 and an Optimize_Click function.

By the way, you should make it clear if you are using Forms and .NET programming or C++/CLI or whatever that is. That isn't standard C++ and is covered that often in this forum. I probably won't be able to help much because I know little to nothing about the interaction of a standard C++ container like vector and System and Form stuff.

I was looking wrong, line 4213 was the the closing brace of the buttoncontrol. I will have to look and try things out I beleive, experiment and see...

Thank you for your help !

you using .NET or something? I never use .NET, but for c at the beginning of your code you could try adding

#define new new(__FILE__, __LINE__)

which should provide file and line information to the debug heap when running in debug mode which would result in something like:

Code:

Debug Error! HEAP CORRUPTION DETECTED: before Normal block(#1262858) at 0x268F3148. CRT detected that the application wrote to memory before start of heap buffer. File: c:\[whatever dir your code in is]\[filename error occurred].cpp (5)

Where that (5) in parenthesis would be where the initial memory that is causing the corruption would be found

i.e.

Code:

line#5: float *a = new float[10]; <--- the originally memory that got corrupted. ... line#500 memset(a - 1, 0, sizeof(float) * 10) <--- follow the var "a" to find the corruption, which occurred here.

Your error sounds like the result of pushing a [non-dynamically allocated] variable onto a "vector" and then modifying it using pointers or incorrectly using one of the c++ standard library functions like strn_cpy(); printf(); etc. on it and then sometime down the line when you goto remove that item from the "vector" it tries to deallocate it, but can't because the memory block is screwed.

I think I already told you not to mix Native and Managed.
Go back to C# and stay with Managed. OR go Native C++.
C++/CLI is standard, but mixing native and managed is not recommended. At least for newbies.

Yes, I use .NET. Thank you for the information. I am not sure if I understand how to use
#define new new(__FILE__, __LINE__) correctly but I think you are right about:
"pushing a [non-dynamically allocated] variable onto a "vector" "

Sometimes I use push_back for vectors and sometimes not. I am just giving them a size and start put strings and int:s, doubles to the elements using count = (count + 1).

Then I do sort these vectors and something might go wrong here. Though sometimes I can run my program as I did a test yesterday, with the exact same procedure, over 60 times in a row and then the Error came up. So the program works but at the same time not.
So not using push_back perheps can cause Errors like this ?
Thanks

>> So not using push_back perheps can cause Errors like this ?
If you access positions that don't exist, then yes. But you can do that with push_back, too.

The problem is occuring when a vector is being destroyed in the Form3::Optimize_Click function. Is there a local vector inside there? Was there anything else lower in the call stack?

Again, as I have mentioned, do not mix native and managed. Scrap your project. You do not know what you are doing.
Stay only native or only managed and these headaches will go away.

This was the lowest in the callstack. I did look carefully in my code, the buttoncontrol contains almost 1500 lines so it is much to look for manually. I did have a feeling that I did something wrong with the vectors and as you said, I did access positions that did not exist.
I also began the acess at 1 and not 0.
So some changes like this did it. It was a vectorproblem.

So I did change this code so now it seems to actully work. An automatic program did press the button for 24 hours(1200 times) with no Errormessage :)
Thank you!

Elysia, I know that I shouldn´t mix managed and unmanaged code.
I know that this is not "correct". But I also ´know´ that it do works, so when you tell me to go managed I do understand completely what you are meening but you are also telling me to rewrite about 2000 lines of code and solutions to managed that I mostly have to learn also.
One day I will but as a ´beginner´ not now.

Even if I go managed, I will have as ´many headaches´ as now. Because I will do wrongs there also but I really do point out that I know that you are right about use managed code.
I mix it now and know that is not ´correct´to do and if I will face big problems that depend on really that, then I have to change it.
I appreciate that you tell me but I wont change it right now.
(I might be wrong)

Quote:

Originally Posted by Coding

sorry if asking but what is the "call stack". Is this something inside VC++ that creates when just debugging the program and not run it ?

The call stack always exists whether the program is in debug mode or not. In debug mode, the call stack might be more informative than it otherwise would be, but it's always there.

Yes okay, that is good to know.

I didn´t know that...

People seem to get all confused and offer wrong suggestions to you since you post in C++ yet use Managed. The new macro, for example, you should avoid, seeing as it may interfere with the managed code.
And if you truly don't listen to anything and still walk down this path, then remember this: Do not mix native and managed in such a way to you use managed types with native containers, or vice versa. Stay in the respective area and keep those areas fully managed or native.

If you try to access non-existant elements in a vector, you will get an assert, or three, in debug, however.

Yes, thanks Elysia. I will keep that in mind. I do listen to what you say ofcourse and I will think about the containers as you mentioned.

Quote:

Originally Posted by Coding

I do listen to what you say ofcourse and I will think about the containers as you mentioned.

Yes, you do listen, but you don't seem to listen when I say don't mix native and managed :)

hehe... one day I will change all my code to only managed, just to much for me to do now ;)