Question

I have created a vector of class objects. The following program crashes with

 "Pointer being freed was not allocated". 

I have deep copied as well. I don’t see where the double delete is happening. What am I missing ?.

    #include <iostream>
    #include <vector>
    using namespace std;

    enum MessageType { HEADER, DATA, CLOSE};

    typedef class bufferElement{

    public:
        char *buffer ; //The actual data
        int64_t length; //length of the data
        MessageType messagetype;    

        /**
         * Copy constructor for the structure
         */
        bufferElement(const struct bufferElement &toCopy)
        {
            std::cout << "Copying the buffer vector - Copy Constructor for buffer" << std::endl;
            buffer = new char[toCopy.length];
            memcpy(buffer,toCopy.buffer,toCopy.length);
            length = toCopy.length;
            messagetype = toCopy.messagetype;
        }


        bufferElement()
        {
            buffer = NULL;
            length =0;
            messagetype = HEADER;
        }

        /**
         *  Initialises the vector element
         *  @param messagetype
         *  what type of message is the particular element.
         *  @param element
         *  The buffer element
         *  @param length_t
         *  The length/size of the buffer element
         */
        bufferElement(char *element, int64_t length_t, MessageType messagetype_t)   //constructor
        {
            std::cout << "The buffer element is Initialized" << std::endl;
            buffer = new char[length_t];
            messagetype = messagetype_t;
            length = length_t;
            memcpy(buffer, element, length_t);
        }

        ~bufferElement()
        {
            std::cout << "Freeing the buffer in the vector - Destructor" << std::endl;
            delete buffer;
            buffer = NULL;
        }


    } messageHolder;

    int main()
    {
        vector<messageHolder> v;
        for(int64_t i=0; i< 1000000000000000000; i++)
        {
            int size = rand()%10000+5;
            char *test = new char[size];
            messageHolder m(test, size, HEADER );
            v.push_back(m);

            if(rand()%3)
            {
                v.erase(v.begin());
            }

        }

        return 0;
    }

Answer 1

I haven’t looked at your code in detail, but if you think you need a copy constructor, you also need an assignment operator. And, why, why, why write this stuff anyway? Why not use std::string? Do you feel the need to write your own floating point types? No, I didn’t think so.