Reading int value from char array after converting to void pointer - c++

Question

I'm trying to build memory chunks of generic data types, but I'm getting garbage when printing the result.
void Read(void* _data, size_t _size, int _position) const
{
char* data = new char[_size];
memcpy(data, m_data + _position - _size, _size);
}
void Write(void* _data, size_t _size, int _position)
{
char* data = new char[_size];
memcpy(m_data + _position, data, _size);
return 1;
}
int main()
{
Chunk c(10);
int value = 10, result;
c.Write(&value, sizeof(int), 0);
c.Read(&result, sizeof(int), sizeof(int));
cout << *((int *)result) << endl;
return 0;
}
What am I doing wrong?

Answer 1

"What am I doing wrong?" - Pretty much everything:
To begin with, both Read and Write functions end with a memory leak, as the allocated-memory pointed by the data local variable is "lost" (no one "knows" the address after the function returns).
In addition, what exactly are you expecting to get by casting (int*)result? It is most certainly not going to be a valid memory address which you can then safely dereference using *((int*)result).

Answer 2

In your read function, the parameter _data is not used, so it won't modify anything. It should be:
void Read(void* _data, size_t _size, int _position)
{
memcpy(_data, m_data + _position - _size, _size);
}
Also, the code to output variable result doesn't make sense, should just be:
cout << result << endl;
As the program is not the complete program, I don't know if there're still other errors