Re: equivalent of realloc in C++

So I did what I probably should have done earlier - sat down and wrote
some code. This first little program only loads lines from a file:

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

int main()
{
    vector<string> vec;
    while ((vec.push_back(string()), getline(cin, vec.back())))
    {
    }
    vec.pop_back();
}

Then I wrote a program that does the same task, except it uses realloc
exclusively. I don't have access to an in-place expansion routine on
Linux (is there one?), so I wrote an implementation that is suboptimal -
it calls realloc *every single pass through the loop*. Pretty silly, eh?

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

int main()
{
    string * vec = 0;
    size_t vecSize = 0;
    for (;; ++vecSize)
    {
        vec = static_cast<string*>
            (realloc(vec, (vecSize + 1) * sizeof(string)));
        if (!vec) return 1;
        new(vec + vecSize) string;
        if (!getline(cin, vec[vecSize])) break;
    }
}

This code is not well-defined because at least in theory string could
hold internal pointers, so realloc is not guaranteed to work. On Gnu it
doesn't, so the code works for the sake of measurements of interest (not
that I'd recommend it).

Now before you take a look at the numbers, I suggest you build a mental
image of what you *believe* the numbers should be. How should the two
versions compare? Then scroll down.