2.vector数组

• 创建vector数组

  vector<int> myint{ 1,2,3,4,5 };

• 尾部插入

  for (int i = 10; i < 20; i++)
  {
      myint.push_back(i);
      
  }

• 读取头部和尾部

  cout << myint.front() << endl;
  cout << myint.back() << endl;

• 动态调整大小

  myint.resize(5);//动态调整大小

• 设置只有六个数据但是缓冲区有90

  myint.resize(6, 90);//设置只有六个数据,但是缓冲有90

• 正向读取

  for (auto ib = myint.begin(), ie = myint.end(); ib != ie; ib++)
  {
      cout << *ib << endl;
  }

• 逆向读取

  for (auto rb = myint.rbegin(), re = myint.rend(); rb != re; rb++)
  {
      cout << *rb << endl;
  }

• 读取

  for (int i = 0; i < myint.size(); i++)
  {
      cout << myint[i] << endl;
  }
  
  for (auto i : myint)
  {
      cout << i << endl;
  }

• 重新初始化

  myint.assign(7, 100);

• 根据位置插入

  auto it = myint.begin() + 3;
  myint.insert(it, 400);//根据位置插入

• 插入一个数组

  int a[5] = { 1,2,3,4,5 };
  myint.insert(it, a, a + 5);//插入一个数组

• 插入一个vector

  vector<int> myintX = { 11,12,13 };
  //批量插入
  myint.insert(it, myintX.begin(), myintX.end());

• 删除和批量删除

  myint.erase(it);
  myint.erase(myint.begin(), myint.begin() + 3);//批量删除

• 调用分配器使用自己分配的内存

  //调用分配器
  vector<int> mymem;
  int *p = mymem.get_allocator().allocate(5);//获取分配器分配内存
  for (int i = 0; i < 5; i++)
  {
      cout << (p[i] = i) << endl;
  }
  myint.get_allocator().deallocate(p, 5);//释放内存

• vector嵌套

  　　//vector嵌套
      vector<int> myint1{ 1,23,4 };
      vector<int> myint2{ 1,23,4 };
      vector<int> myint3{ 1,23,4 };
      vector<vector<int>> myallint{ myint1,myint2,myint3 };
      for (auto i : myallint)
      {
          for (auto j : i)
          {
              cout << j << endl;
          }
      }