Question

我一直在尝试以索引作为键来制作每个循环这种情况我想做一个逻辑，如果输入用户与索引匹配，我将显示foreach所有的索引作为键的数据

我做了两个这样的课程

class DataContainer
    {

        public DataContainer()
        {

        }


        public int index { get; set; }
        public List<DataValue> DataValue { get; set; }
    }
    class DataValue
    {
        public DataValue()
        {

            IntegerValues = new List<int>();
        }
        public string name { get; set; }
        public List<int> IntegerValues { get; set; }
    }

之后我尝试制作像这样的datacontainer列表

List<DataContainer> harakatSininilMabsutoh = new List<DataContainer>(){
        new DataContainer{index = 2015 , DataValue = new List<DataValue>()
         {
             new DataValue{name = "first",IntegerValues = {9,55,18,11}},
             new DataValue{name = "second"   ,IntegerValues = {5,54,18,11}},
             new DataValue{name = "third" ,IntegerValues = {40,26,14,11}},
             new DataValue{name = "four"    ,IntegerValues = {22,0,5,10}},
             new DataValue{name = "fifth"    ,IntegerValues = {46,44,17,0}},

         }
         },
          new DataContainer{index = 2013 , DataValue = new List<DataValue>()
         {
             new DataValue{name = "first",IntegerValues = {26,49,8,11}},
             new DataValue{name = "second"   ,IntegerValues = {19,42,8,11}},
             new DataValue{name = "third" ,IntegerValues = {55,3,12,11}},
             new DataValue{name = "fourth"    ,IntegerValues = {27,4,23,8}},
             new DataValue{name = "fifth"    ,IntegerValues = {43,22,7,1}},

         }
         },
          new DataContainer{index = 2001, DataValue = new List<DataValue>()
         {
             new DataValue{name = "first",IntegerValues = {35,44,27,10}},
             new DataValue{name = "second"   ,IntegerValues = {24,41,27,10}},
             new DataValue{name = "third" ,IntegerValues = {36,30,26,10}},
             new DataValue{name = "fourth"    ,IntegerValues = {59,24,8,6}},
             new DataValue{name = "fifth"    ,IntegerValues = {29,27,26,1}},

         }
          }
   };

然后我做了一个像这样的逻辑

    int years = (this is user input);
    if(years == 2015)
{
    ///How to for each this which has index 2015
}
else if (years = 2013)
{
         //how to foreach this which has index 2013
}
else if (years = 2001)
{
         //how to foreach this which has index 2001

Answer 1

首先请注意，在此行中，您尝试使用类型名称作为属性名称：

public List<DataValue> DataValue { get; set; }

我已将此属性重命名为'DataValues'，如下所示：

public List<DataValue> DataValues { get; set; }

你有一个列表（'harakatSininilMabsutoh'），其中每个元素都是一个DataContainer。列表中的每个DataContainer都有两个属性：索引和'DataValues'列表（NB在帖子中从'DataValue'重命名）。

您想要的循环逻辑将是这样的：

var matchingYears = harakatSininilMabsutoh.Where(h => h.index == years);

foreach (var dataContainer in matchingYears)
{
    foreach (var item in dataContainer.DataValues)
    {
        // Action required on each DataValue:
        Debug.Print(item.name + " " + string.Join(",", item.IntegerValues));
    }
}

您需要将以下'using'语句添加到您的类中，因为'Where'是LINQ扩展方法：

using System.Linq;

如果您知道将只有一个匹配年份，则可以添加First()并删除外部foreach循环。如果您知道最多只有一个匹配年份（但可能为零），您仍然可以移除外部foreach循环，但您应该使用FirstOrDefault()代替并测试null。

Answer 2

最简单的方法是使用LINQ FirstOrDefault这样的

int userinput = 2015;
DataContainer requested = harakatSininilMabsutoh.FirstOrDefault(x => x.index == userinput);
if (requested == null) //FirstOrDefault of a class will return null if not found
    return;
foreach (DataValue val in requested.DataValue) 
    Console.WriteLine(val.name + ": " + string.Join(", ", val.IntegerValues));

编辑2：

如果你只需要所有整数，没有名字，没有其他任何东西，那么你可以这样做以获得List<List<int>>：

int userinput = 2015;
List<List<int>> intValuesOnly = harakatSininilMabsutoh
    .FirstOrDefault(x => x.index == userinput)
    .DataValue
    .Select(y => y.IntegerValues)
    .ToList();
//Do whatever you want with intValuesOnly. This is everything that you have in a list of lists

或执行此操作以获取List<int>（展平）：

int userinput = 2015;
List<int> intValuesOnly = harakatSininilMabsutoh
    .FirstOrDefault(x => x.index == userinput)
    .DataValue
    .SelectMany(y => y.IntegerValues)
    .ToList();
//Do whatever you want with intValuesOnly. This is everything that you have in single list

如果找不到FirstOrDefault，null可能会返回userinput，请注意，如果您不使用C＃6，您可能需要考虑两个步骤LINQ：

int userinput = 2015;
DataContainer requested = harakatSininilMabsutoh.FirstOrDefault(x => x.index == userinput);
if (requested == null) //FirstOrDefault of a class will return null if not found
    return;
List<List<int>> intValuesOnly = requested
    .Select(y => y.IntegerValues)
    .ToList();
//Do whatever you want with intValuesOnly. This is everything that you have in a list of lists

foreach循环数据索引作为关键

2 个答案: