c/c++ 标准库 vector

标准库 vector的小例子

test1~test7

#include <iostream>

#include <vector>

using namespace std;

class A{

public:

  A(){cout << "AA" << endl;}

};

int main(){

  //test1

  /*

  vector<int> v1;

  vector<vector<string>> v2;

  */

  //test2

  /*

  vector<A> v3(2);//创建2个元素的vector

  //因为v4所提供的值不能作为元素的初始值，

  //所以编译器尝试用默认值初始化vector，所以{4}的含义就变成了(4),

  //也就是创建了4个元素的vector

  vector<A> v4{4};//创建4个元素的vector

  vector<int> v5{15};//创建1个元素的vector

  for(auto a : v5){

    cout << a << endl;

  }

  */

  //test3

  /*

  vector<int> v1;//size:0

  cout << v1.size() << endl;

  vector<int> v2(10);//size:10

  cout << v2.size() << endl;

  vector<int> v3(10, 12);//size:10

  cout << v3.size() << endl;

  vector<int> v4{11};//size:1

  cout << v4.size() << endl;

  vector<int> v5{10, 12};//size:2

  cout << v5.size() << endl;

  vector<string> v6{10};//size:10

  cout << v6.size() << endl;

  vector<string> v7{10, "ab"};//size:10

  cout << v7.size() << endl;

  */

  //test4

  /*

  vector<int> v;

  int s;

  while(cin >> s){

    v.push_back(s);

  }

  cout << v.size() << endl;

  */

  //test5

  /*

  vector<string> v;

  string s;

  while(cin >> s){

    v.push_back(s);

  }

  cout << v.size() << endl;

  */

  //test6

  /*

  //vector::size_type t;编译不过，必须带<int>

  vector<int>::size_type t;

  */

  //test7

  /*

  vector<int> v(11, 0);

  int grade;

  while(cin >> grade){

    if(grade <= 100)

      ++v[grade / 10];

  }

  for(auto a : v){

    cout << a << " ";

  }

  cout << endl;

  */

}