c/c++ 标准库 vector

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;                                                                 
  */

}