Question

Consider the following code snippet:

std::vector<int> v;
v.reserve(100);
v.insert(v.end(), 100, 5);

v.erase(v.begin(), v.end());

std::cout << v.capacity << std::endl;

This prints out 100. Does it mean that vector still holds the 100 memory locations? Is it required to call reserve(0) after calling erase(begin,end) on a vector, to relinquish all space held by the vector?

Answer 1

You are looking for the (in)famous swap trick:

vector<T>().swap(myVector);

See here for backgrounder

How to downsize std::vector?