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Top Forums Programming Pointer to a struct (with pointers) *** glibc detected *** double free Post 302264943 by otheus on Friday 5th of December 2008 07:31:43 AM
Old 12-05-2008
I think the code looks okay (but I'm not a C++ expert). It could be that x and y no longer hold the original reference to your allocated arrays. In that case, the pointers might point somewhere they did not originally. Try this: after instantiating the m_Genes object, create a "shallow copy" of it, then before you distruct, compare the shallow copy with the m_Genes copy. If there's a difference in pointer values, that might be your problem.

Another possibility just occurred to me: It could be that you made a shallow copy of m_Genes and deleted the shallow copy as if it were a deep copy. That is, you already freed the pointers in m_Genes->x and ->y.
 

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QStrList(3qt)															     QStrList(3qt)

NAME
QStrList - Doubly-linked list of char* SYNOPSIS
#include <qstrlist.h> Inherits QPtrList<char>. Inherited by QStrIList. Public Members QStrList ( bool deepCopies = TRUE ) QStrList ( const QStrList & list ) ~QStrList () QStrList & operator= ( const QStrList & list ) DESCRIPTION
The QStrList class provides a doubly-linked list of char*. If you want a string list of QStrings use QStringList. This class is a QPtrList<char> instance (a list of char*). QStrList can make deep or shallow copies of the strings that are inserted. A deep copy means that memory is allocated for the string and then the string data is copied into that memory. A shallow copy is just a copy of the pointer value and not of the string data itself. The disadvantage of shallow copies is that because a pointer can be deleted only once, the program must put all strings in a central place and know when it is safe to delete them (i.e. when the strings are no longer referenced by other parts of the program). This can make the program more complex. The advantage of shallow copies is that they consume far less memory than deep copies. It is also much faster to copy a pointer (typically 4 or 8 bytes) than to copy string data. A QStrList that operates on deep copies will, by default, turn on auto-deletion (see setAutoDelete()). Thus, by default QStrList will deallocate any string copies it allocates. The virtual compareItems() function is reimplemented and does a case-sensitive string comparison. The inSort() function will insert strings in sorted order. In general it is fastest to insert the strings as they come and sort() at the end; inSort() is useful when you just have to add a few extra strings to an already sorted list. The QStrListIterator class is an iterator for QStrList. See also Collection Classes, Text Related Classes, and Non-GUI Classes. MEMBER FUNCTION DOCUMENTATION
QStrList::QStrList ( bool deepCopies = TRUE ) Constructs an empty list of strings. Will make deep copies of all inserted strings if deepCopies is TRUE, or use shallow copies if deepCopies is FALSE. QStrList::QStrList ( const QStrList & list ) Constructs a copy of list. If list has deep copies, this list will also get deep copies. Only the pointers are copied (shallow copy) if the other list does not use deep copies. QStrList::~QStrList () Destroys the list. All strings are removed. QStrList &; QStrList::operator= ( const QStrList & list ) Assigns list to this list and returns a reference to this list. If list has deep copies, this list will also get deep copies. Only the pointers are copied (shallow copy) if the other list does not use deep copies. SEE ALSO
http://doc.trolltech.com/qstrlist.html http://www.trolltech.com/faq/tech.html COPYRIGHT
Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com. See the license file included in the distribution for a complete license statement. AUTHOR
Generated automatically from the source code. BUGS
If you find a bug in Qt, please report it as described in http://doc.trolltech.com/bughowto.html. Good bug reports help us to help you. Thank you. The definitive Qt documentation is provided in HTML format; it is located at $QTDIR/doc/html and can be read using Qt Assistant or with a web browser. This man page is provided as a convenience for those users who prefer man pages, although this format is not officially supported by Trolltech. If you find errors in this manual page, please report them to qt-bugs@trolltech.com. Please include the name of the manual page (qstrlist.3qt) and the Qt version (3.3.8). Trolltech AS 2 February 2007 QStrList(3qt)
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