Getting the size in bytes of a vector [duplicate]

Question

Sorry for this maybe simple and stupid question but I couldn't find it anywhere.

I just don't know how to get the size in bytes of a std::vector.

std::vector<int>MyVector;   
/* This will print 24 on my system*/   
std::cout << "Size of  my vector:\t" << sizeof(MyVector) << std::endl;

for(int i = 0; i < 1000; i++)
   MyVector.push_back(i);

/* This will still print 24...*/    
std::cout << "Size of  my vector:\t" << sizeof(MyVector) << std::endl;

So how do I get the size of a vector?! Maybe by multiplying 24 (vector size) by the number of items?

Answer 1

Vector stores its elements in an internally-allocated memory array. You can do this:

sizeof(std::vector<int>) + (sizeof(int) * MyVector.size())

This will give you the size of the vector structure itself plus the size of all the ints in it, but it may not include whatever small overhead your memory allocator may impose. I'm not sure there's a platform-independent way to include that.