C++ vector 容器

//vector类  resemble array  自动扩容...  暂存于内存中
//格式 vector<类（型）名> 对象名  example: vector<string> v; vector<int> i;
//copy a entire file into a vector of string
#include<fstream>
#include<string>
#include<iostream>
#include<vector>
using namespace std;
int main()
{
 vector<string> v;
 string  s;
 ofstream out("file.txt");
 for (int i = 0; i < 3; i++)
 {
  cout << "Please enter:" << endl;
  getline(cin, s);
  out << s << '\n';
 }
 out.close();
 ifstream in("file.txt");
 while (getline(in, s))//按行读取
  v.push_back(s);  //将string s压入vector v的尾部
 for (int i = 0; i < v.size(); i++)
  cout <<i<<":"<< v[i] << endl;
 for (int i = 0; i < v.size(); i++)
  v[i] += "!";//可以根据下标改变单元的值
 for (int i = 0; i < v.size(); i++)
  cout << i << ":" << v[i] << endl;
 system("pause");
 return 0;
}