Question

Please what wrong in this code:

#include <iostream>
#include <vector>


unsigned __int32 ConvertToChars(std::vector<int> container, char** pChars)
{
    *pChars = (char*)&container[0];

    return container.size() * sizeof(int);
}


void ConvertToIntegers(char* chars, short size, std::vector<int>& container)
{
    int count = size / sizeof(int);

    int* pIntegers = (int*)chars;

    for(int i=0; i < count; ++i)
    {
        container.push_back(*(pIntegers++));
    }
}


void Print(const std::vector<int>& container)
{
    for(int i=0; i < container.size(); ++i)
    {
        std::cout << container[i] << std::endl;
    }
}


void main()
{
    std::vector<int> vec1;

    vec1.push_back(1);
    vec1.push_back(2);
    vec1.push_back(3);

    char* buffer = 0;

    short bufferSize = ConvertToChars(vec1, &buffer);

    std::vector<int> vec2;

    ConvertToIntegers(buffer, bufferSize, vec2);

    Print(vec2);

    char c;

    std::cin >> c;
}

function Print prints values:

• -572662307
• -842150451
• -572662307

Thank you!!!

Answer 1

You’re copying the container when you pass it to ConvertToChars, then taking a pointer to one of its elements, then seeing the copy go out of scope, which invalidates your pointer.