[RESOLVED] Error on destruction of boost::shared_ptr
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Thread: [RESOLVED] Error on destruction of boost::shared_ptr

  1. #1
    Join Date
    Oct 2010
    Posts
    7

    [RESOLVED] Error on destruction of boost::shared_ptr

    I have an stl vector of boost::shared_ptr's declared like so:
    vector< shared_ptr<delim_list> > row_data;

    delim_list is a custom class encapsulating a vector of strings.

    The container is filled like this:
    shared_ptr<delim_list> insert_list(new delim_list(line, ','));
    row_data.push_back(insert_list);

    When the row_data vector goes out of scope there is a access memory reading violation thrown from the std::string library.

    I am using VS2005 and am quite at a loss. The code worked when I was using raw pointers, but am now trying to use smart pointers to save time and gain security.

    PS: Are there any code tags for these posts?

    Thanks,
    Ian

  2. #2
    Lindley is offline Elite Member Power Poster
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    Fairfax, VA
    Posts
    10,888

    Re: Error on destruction of boost::shared_ptr

    Yes there are code tags.

    You probably corrupted an object somewhere with an out-of-bounds write.

    I *have* seen a case where a shared pointer to an object containing another shared pointer and so on (basically a linked list) errored on destruction due to stack overflow trying to destroy all the shared_ptrs. But if that isn't your problem then it's probably some form of corruption.

  3. #3
    Join Date
    Oct 2010
    Posts
    7

    Re: Error on destruction of boost::shared_ptr

    Okay,

    When you say corruption you mean something perhaps trying to destruct an object twice? Like perhaps the delim_list destructor of the elements of the vector get called before the shared_ptr goes out of scope, or vis-versa.

    Just for clarity this is the delim_list classes declaration;

    Code:
    class delim_list
    {
    private:
    	char delimiter;
    	vector<string> delim_vec;
    	string delim_str;
    public:
    	delim_list(const string& str, char delim);
    	delim_list(vector<string>& vec, char delim);
    	delim_list(char delim);
    	const string& to_string(){return delim_str;}
    	const vector<string>& to_vector(){return delim_vec;}
    	void push_back(const string& str);
    };
    And here is the full code that loads it
    Code:
    //This is a virtual function called from the constructor of CSV_File.
    void CSV_File::load_data(ifstream& csv_file)
    {
    	string line;
    	string cell;
            
            //loop through lines in a file and add lines to row_data
    	while (getline(csv_file,line))
    	{
    	    stringstream line_stream(line);
       	    counted_ptr<delim_list> insert_list(new delim_list(line, ','));
    	    row_data.push_back(insert_list);
            }
    }
    So no shared pointer in whats being pointed to. So it must be some sort of corruption. I was a little worried about creating the string 'line' on the stack and then passing it by reference into the constructor for delim_list to create the vector elements, but I think its okay.

  4. #4
    Join Date
    Oct 2010
    Posts
    7

    Re: Error on destruction of boost::shared_ptr

    It looks like I misplaced the location of the error, but its still puzzling. I have a std::auto_ptr to that delim_list class that I declare as a class variable and set during construction. But it is inaccessible after that.

    The part of the constructor that sets it looks like this.
    Code:
    //variables line and cell are local to the constructor
    string line;
    string cell;
    getline(csv_file, line);
    
    //load the line into a string stream
    stringstream line_stream(line);
    
    header = new delim_list(line, ',');
    When I call the to_string method (posted earlier) of the delim_list object referenced by the auto_ptr, I get access memory violations. This same problem causes the code to throw an error when the auto_ptr goes out of scope.

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