C++中vector容器 assign()用法

assign函数:
函数原型：
void assign(const_iterator first,const_iterator last);
void assign(size_type n,const T& x = T());
功能：
将区间[first,last)的元素赋值到当前的vector容器中，或者赋n个值为x的元素到vector容器中，这个容器会清除掉vector容器中以前的内容。
实例：

#include 
#include 
int main( )
{
 using namespace std;
 vector v1, v2, v3;
 vector::iterator iter;
 v1.push_back(10);
 v1.push_back(20);
 v1.push_back(30);
 v1.push_back(40);
 v1.push_back(50);
 v2.push_back(1);
 v2.push_back(2);
 cout << "v1 = " ;
 for (iter = v1.begin(); iter != v1.end(); iter++)
  cout << *iter << " ";
 cout << endl;
cout << "v2 = ";
 for (iter = v2.begin(); iter != v2.end(); iter++)
  cout << *iter << " ";
 cout << endl;
 v2 = v1;
 cout << "v2 = ";
 for (iter = v2.begin(); iter != v2.end(); iter++)
  cout << *iter << " ";
 cout << endl;
 v2.assign(v1.begin(), v1.end());
 cout << "v2 = ";
 for (iter = v2.begin(); iter != v2.end(); iter++)
  cout << *iter << " ";
 cout << endl;
 v3.assign(7, 3) ;
 cout << "v3 = ";
 for (iter = v3.begin(); iter != v3.end(); iter++)
  cout << *iter << " ";
 cout << endl;
 return 0;
}

结果如下：

v1 = 10 20 30 40 50

v2 = 1 2

v2 = 10 20 30 40 50

v2 = 10 20 30 40 50

v3 = 3 3 3 3 3 3 3 (7个3)