问题描述
我有以下对象：
class Car{
int price;
string color;
string size;
}
var list = new List<Car>();
list.Add...//add 20 cars
//I Now want to select from this list any cars whose color and size matches that of any other car
list.Select(car => String.Join(car.color,car.size))
我想从此列表中选择一组字符串（颜色+大小），这些字符串存在于列表中的多辆汽车中
不知道该如何继续使用linq，因为我一直对此深感不安
解决方法
var groupedCars = list.
GroupBy(c => c.color + c.size,c => c).
Where(g => g.Count() > 1);
您应该先用/*
Poetry In Motion; Cortez Phenix
This program allows the user to make a poem,and the program contains a
poem game. The most notable features are loops controlled by the user.
*/
#include <string>
#include <iostream>
using namespace std;
void makePoem()
{
string poem;
string user_input;
cout << "Enter a poem of your own creation,one line at a time.\n";
cout << "Type 'quit' to exit the program.\n\n";
cout << "Type your poem,pressing the enter key to create a new line.\n\n";
while (getline(cin,user_input))
{
if (user_input == "quit")
break;
poem += user_input;
poem += '\n';
}
cout << "\nGoodbye! Have a great day.\n";
}
int main()
{
makePoem();
return 0;
}
和color group the list，然后选择size大于1的项目
Count此外，您应将var result = list
.GroupBy(c => string.Join(c.color,c.size))
.Where(g => g.Count() > 1)
.Select(g => g.Key)
.ToList();
和color标记为size字段（或使用属性，这是更好的选择）