vs for while循环中的C迭代器行为

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

int main()
{
  vector<int> v;
  set<int> s;

  // add integers 0..5 to vector v and set s
  for (int i = 0; i < 5; i++) {
    v.push_back(i);
    s.insert(i);
  }

  cout << "Iterating through vector with for loop.n";
  vector<int>::const_iterator itv;
  for (itv = v.begin(); itv != v.end(); itv++) cout << *itv << ' ';
  cout << 'n';

  cout << "Iterating through set with for loop.n";
  set<int>::const_iterator its;
  for (its = s.begin(); its != s.end(); its++) cout << *its << ' ';
  cout << 'n';

  cout << "Iterating through vector with while loop.n";
  itv = v.begin();
  while (itv++ != v.end()) cout << *itv << ' ';
  cout << 'n';

  cout << "Iterating through set with while loop.n";
  its = s.begin();
  while (its++ != s.end()) cout << *its << ' ';
  cout << 'n';
}

以上产生：

Iterating through vector with for loop.
0 1 2 3 4 
Iterating through set with for loop.
0 1 2 3 4 
Iterating through vector with while loop.
1 2 3 4 0 
Iterating through set with while loop.
1 2 3 4 5

for循环按预期工作,但不是while循环.由于我用作后缀,我不明白为什么while循环的行为与它们一样.另一个谜团是为什么while循环为set s打印5,因为这个数字没有插入s中.