vector_clear

// clearing vectors
#include <iostream>
#include <vector>

using namespace std;

//clear的内容
//从向量中移除所有元素(已销毁)，使容器的大小为0。
//不能保证重新分配会发生，也不能保证由于调用此函数而改变向量容量。
//强制重新分配的典型替代方法是使用swap:
//向量T < > () .swap (x);//清除x重新分配

int main ()
{
  vector<int> myvector;
  myvector.push_back (100);
  myvector.push_back (200);
  myvector.push_back (300);

  cout << "myvector contains:";
  for (unsigned i=0; i<myvector.size(); i++)
    cout << ' ' << myvector[i];
  cout << '\n';

  myvector.clear();

  myvector.push_back (1101);
  myvector.push_back (2202);

  cout << "myvector contains:";
  for (unsigned i=0; i<myvector.size(); i++)
    cout << ' ' << myvector[i];
  cout << '\n';

    for(vector<int>::iterator it=myvector.begin();it!=myvector.end();++it)
        cout<<*it<<" ";
        cout<<endl;
  return 0;
}

/*
Output:
myvector contains: 100 200 300
myvector contains: 1101 2202

*/