*** glibc detected *** double free or corruption: 0x40236ff4 ***


 
Thread Tools Search this Thread
Top Forums Programming *** glibc detected *** double free or corruption: 0x40236ff4 ***
# 1  
Old 05-17-2006
*** glibc detected *** double free or corruption: 0x40236ff4 ***

when i try to use the class i wrote, i either get this:

*** glibc detected *** double free or corruption: 0x40236ff4 ***
and the proccess exits with an error code of 0;

or it segfaults. could someone look at my header file (with imp.) to give me some insight as to why its not working?


Code:
#ifndef _DYNAMICARRAY_H
#define _DYNAMICARRAY_H

/*****
Written by Joseph Oldak
May 2006
*****/

using namespace std;

template <class T>
class Dynamicarray
{
	public:
	
	Dynamicarray();
	Dynamicarray(int s);
	~Dynamicarray();
	void add(T elem);
	T get_val(int loc);	// returns first element if element requested does not exist.
	void erase(int loc); // location
	T * init_ptr();
	int size();
	
	private:
		
	int Size;
	T * buffer;
	T * ptr;
};

template <class T>
Dynamicarray<T>::Dynamicarray()
{
	Size = 0;
	ptr = init_ptr();
	
	//ptr = new T[Size];
}

template <class T>
Dynamicarray<T>::Dynamicarray(int s)
{
	Size = s;
	ptr = init_ptr();
	//ptr = new T[Size];
}


template <class T>
Dynamicarray<T>::~Dynamicarray()
{
	if(ptr != NULL)
	{
		delete[] ptr;
		ptr = NULL;
	}
	
	if(buffer != NULL)
	{
		delete[] buffer;
		buffer = NULL;
	}
}

template <class T>
T* Dynamicarray<T>::init_ptr()
{
	return new (nothrow) T[Size];
	
}

template <class T>
void Dynamicarray<T>::add(T elem)
{
	int sbuffer;

	buffer = new T[Size+1];
	sbuffer = Size+1;

	for  (int  i = 0; i < Size; i ++)
	{
		buffer[i] = ptr[i];
	}

	delete ptr;

	Size = sbuffer;

	buffer[Size-1] = elem;

	ptr = new T[Size];

	for(int  i = 0; i < Size; i ++)
	{
		ptr[i] = buffer[i];
	}
	delete[] buffer;
	buffer = NULL; 
	
}

template <class T>
T Dynamicarray<T>::get_val(int loc)
{
	if (loc > Size)
	{
		return ptr[0];
	}
	
	return ptr[loc];
}

template <class T>
void Dynamicarray<T>::erase(int loc)
{
	if(get_val(loc) != -1)
	{
		int sbuffer;	
		
		buffer = new T[Size-1];
		sbuffer = Size-1;
		
		for(int i = 0; i < loc; i++)
		{
			buffer[i] = ptr[i];
		}
		

		for(int i = loc+1; i < Size; i++)
		{
			buffer[i] = ptr[i];
		}

		Size = sbuffer;

		for(int i = 0; i <  Size; i++)
		{
			ptr[i] = buffer[i];
		}

		delete[] buffer;
		buffer = NULL;
	}
}

template <class T>
int Dynamicarray<T>::size()
{
	return Size;
}	


#endif /* _DYNAMICARRAY_H */


Last edited by norsk hedensk; 05-18-2006 at 12:21 PM..
# 2  
Old 05-17-2006
after looking through it again, i see that i have to trace my pointer usage a lot better, ill post back when i fix it.
# 3  
Old 05-18-2006
i fixed some small typeos i had here and there. the problem is happening right in the constructor as far as i can tell.

so the default constructor
Code:
template <class T>
Dynamicarray<T>::Dynamicarray()
{
	Size = 0;
	ptr = init_ptr();
	
	//ptr = new T[Size];
}

calls
Code:
init_ptr()

which returns
Code:
new (nothrow) T[Size];

init_ptr() is of type T* , and ptr is of type T*, i dont understand why this isnt working.

it worked before without templates, specifying the type of the pointer, so i can only assume my usage of templates is incorrect. can anyone shed any light on this?

even if i comment out all the code in the constructors except the Size = 0; or = s; it still segfaults.

i guess it has to be a problem with the template usage.
# 4  
Old 05-18-2006
Is it legal to allocate an array of size zero? I know you can in C, it just bumps the size up to the minimum, but in C++, I'm not so sure.

[edit] Occurred to me that it could be something in T crashing, rather than the template class

Last edited by Corona688; 05-18-2006 at 01:02 PM..
# 5  
Old 05-18-2006
Quote:
Originally Posted by Corona688
Is it legal to allocate an array of size zero? I know you can in C, it just bumps the size up to the minimum, but in C++, I'm not so sure.

[edit] Occurred to me that it could be something in T crashing, rather than the template class
i thought that might be the problem as well, but it does it even if i set the size to something bigger than zero, it also does it if there is no pointer initiliazation at all.
# 6  
Old 05-18-2006
heres how im calling the constructors if it helps:

Code:
Dynamicarray<type> newArray (size);

i am expecting to be able to use the member functions as such:

Code:
newArray.get_val(location);

i am using templates in the correct manner, no?
# 7  
Old 05-19-2006
If you weren't using it in the correct way it'd give compilation errors, not crashes. They're very picky.

Code:
if (loc > Size)

should be
Code:
if (loc >= Size)

but that may not be the problem either. We really need to see ALL the code.

Also:
Code:
T Dynamicarray<T>::get_val(int loc)

should be
Code:
T &Dynamicarray<T>::get_val(int loc)

That way, it doesn't copy the object. That can cause crashes when the object itself contains allocated things -- when the copy goes out of scope, it frees the resources for both, and the next time you use it, you're using data that's been freed then freeing data that's already been freed...

Last edited by Corona688; 05-19-2006 at 12:06 AM..
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Homework & Coursework Questions

FORTRAN error *** glibc detected ***

Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted! 1. The problem statement, all variables and given/known data: I'm doing aproximation of derivative called five-point stencil. For every value of x, in interval , in step... (0 Replies)
Discussion started by: antonija
0 Replies

2. Programming

C++ glibc detected double free or corruption(!prev) using shared library

Currently I test a shared library vendor provided in linux , the following is the simple source : #include <iostream> using namespace std; extern int test1(); extern int test2(); int main() { cout << "hello world" << endl ; return 0 ; cout << "Test 1" << endl; ... (6 Replies)
Discussion started by: barfatchen
6 Replies

3. Programming

*** glibc detected *** ./a.out malloc() memory corruption

I am facing a problem of memory corruption. The loop runs for the first time but does not go through the second time. What could be the problem? for(int z=0;z<2;z++) { fp=fopen("poly.dat","r"); /*do something which reads this file into a 2D array*/ fclose(fp); ... (10 Replies)
Discussion started by: dare
10 Replies

4. Programming

FORTRAN: double free or corruption

Hello. I'm looking for a quite "interesting" bug I'm using fortran 90, compiler gfortran and the main idea is for every time step I build a bin structure for search contact between particles, for this at the begining TYPE :: circle_index INTEGER(kind = 4) :: ind_p TYPE(circle_index),... (1 Reply)
Discussion started by: Marce
1 Replies

5. Programming

*** glibc detected *** : malloc(): memory corruption (fast)

Hi Friends, while executing the below code, am getting *** glibc detected *** ./ok: malloc(): memory corruption (fast) error, please suggest how to solve this issue. #include <stdio.h> #include <string.h> #include <sqlca.h> #include <alloca.h> /* Define constants for VARCHAR... (2 Replies)
Discussion started by: mpjobsrch
2 Replies

6. Programming

*** glibc detected *** ./a.out: malloc(): memory corruption (fast):

*** glibc detected *** ./a.out: malloc(): memory corruption (fast): Posted A minute ago M trying to make multiway tree and dont know what happend when this part of code get executed: 01void ins(NODE *ptr) 02{ 03 //working 04 if(ptr!=NULL) 05 { 06 SNODE *var=NULL; 07 var=(SNODE... (3 Replies)
Discussion started by: exgenome
3 Replies

7. Programming

solved: glibc detection corruption using a fork in popen

Hi, I am having a hell of a time getting this to work. So basically, I have opened a popen to run a program that is going to prompt an action to occur half way through, when it gets to this I need to create a separate process and do some stuff, then return to the original process. This works... (0 Replies)
Discussion started by: imrank27
0 Replies

8. Programming

Why does this occur? *** glibc detected *** malloc(): memory corruption: 0x10013ff8 ***

there seems not to be error in this segment. In some computers, it can work well. But in others, it will give a failure. why it ocurrs and how to deal with it? in a function: if( *ver == NULL ) { *ver = (vertex *) malloc(sizeof(vertex)); //this line ... (17 Replies)
Discussion started by: cdbug
17 Replies

9. Programming

Pointer to a struct (with pointers) *** glibc detected *** double free

I am using a structure defined as follows struct gene_square { double *x; double *y; };I have class, with a member function which is a pointer of this type: gene_square* m_Genes;I am allocating memory in the constructors like this: m_Genes = new gene_square; for (ii=0;... (1 Reply)
Discussion started by: jatoo
1 Replies

10. Programming

*** glibc detected *** free(): invalid next size (normal): 0x0000000000503e70 ***

hi, I have made a small C program that make use of malloc and free for processing bitmap images. when i try to run the program, I am getting a error something like *** glibc detected *** free(): invalid next size (normal): 0x0000000000503e70 *** I am not sure of which free() is causing this... (1 Reply)
Discussion started by: vbreddy
1 Replies
Login or Register to Ask a Question