Question

我创建了一个数据类型为List的数组，如下所示：

List<string>[] phase2 = new List<string>[200];

有很多初始化（这是一个简单的示例）：

    phase2[0] = new List<string>() { "Bob", "Complex", "B", "AOT", "Yes", "Yes", "Yes", "Yes", };
    phase2[1] = new List<string>() { "Jim", "Complex", "B", "AOT", "Yes", "Yes", "Yes", "Yes" };
    phase2[2] = new List<string>() { "Joe", "Complex", "A", "AOT", "zNO", "Yes", "Yes", "Yes" };
    phase2[3] = new List<string>() { "Bill", "Complex", "A", "AOT", "Yes", "Yes", "Yes", "Yes" };
    phase2[4] = new List<string>() { "Robert", "Complex", "A", "PL", "zNO", "Yes", "Yes", "Yes" };

我想知道如何在索引3中搜索已初始化的所有数组中的字符串“ B”？

还有一个好处（不确定是否可行），您可以在DIFFERENT索引中搜索MULTIPLE字符串吗？例如，我想返回所有在索引3中具有字符串值“ B”，在索引5中具有字符串值“是”的列表。

任何帮助将不胜感激。

编辑：感谢您的所有答复！我还没有了解linq，所以很多答案都在我头上。感谢lollercoasters提供的愚蠢解决方案：）

Answer 1

如果您希望更好地理解非Linq lambda解决方案，请在此处进行配合：

List<string>[] phase2 = new List<string>[200];
phase2[0] = new List<string>() { "Bob", "Complex", "B", "AOT", "Yes", "Yes", "Yes", "Yes", };
phase2[1] = new List<string>() { "Jim", "Complex", "B", "AOT", "Yes", "Yes", "Yes", "Yes" };
phase2[2] = new List<string>() { "Joe", "Complex", "A", "AOT", "zNO", "Yes", "Yes", "Yes" };
phase2[3] = new List<string>() { "Bill", "Complex", "A", "AOT", "Yes", "Yes", "Yes", "Yes" };
phase2[4] = new List<string>() { "Robert", "Complex", "A", "PL", "zNO", "Yes", "Yes", "Yes" };

for (int i = 0; i < phase2.Length; i++)
{
  var list = phase2[i];
  if (list == null) continue; // skip empty lists
  if (list[2] == "B" && list[4] == "Yes")
  {
    // found elements in list
    Console.WriteLine("found elements in list at index: " + i);
  }
}

Answer 2

这是LINQ的实现方法：

static void Main(string[] args)
{
    List<string>[] phase2 = Enumerable.Repeat(new List<string>(), 200).ToArray();

    phase2[0] = new List<string>() { "Bob", "Complex", "B", "AOT", "Yes", "Yes", "Yes", "Yes", };
    phase2[1] = new List<string>() { "Jim", "Complex", "B", "AOT", "Yes", "Yes", "Yes", "Yes" };
    phase2[2] = new List<string>() { "Joe", "Complex", "A", "AOT", "zNO", "Yes", "Yes", "Yes" };
    phase2[3] = new List<string>() { "Bill", "Complex", "A", "AOT", "Yes", "Yes", "Yes", "Yes" };
    phase2[4] = new List<string>() { "Robert", "Complex", "A", "PL", "zNO", "Yes", "Yes", "Yes" };

    List<string>[] result = phase2?.Where(x => x.Any(y => y == "B")).ToArray();
}

Answer 3

简而言之，请记住，阶段2中的每个元素都是一个列表，因此它实现了Enumerable，因此打开了所有LINQ功能。使用您提供的功能（谓词），立即就会想到查找。

https://docs.microsoft.com/en-us/dotnet/api/system.collections.generic.list-1.find?view=netframework-4.7.2

如果您研究此途径，将会学到很多东西。

Answer 4

您可以使用Linq搜索具有与您的参数匹配的元素的所有列表，如下所示：

phase2.Where(list => list.Any(item => item == "string to search for"));

Answer 5

以下是可以帮助您的课程：

public class ListFilterer
{
    private readonly List<string>[] _searchSpace;

    public ListFilterer(List<string>[] searchSpace)
        => this._searchSpace = searchSpace ?? new List<string>[0];

    public IEnumerable<List<string>> GetListsHaving(params Tuple<int, string>[] query)
        => (from l in _searchSpace
            where AllConditionsMatch(l, query)
            select l);

    private static bool AllConditionsMatch(IReadOnlyList<string> lst, IEnumerable<Tuple<int, string>> conditions)
    {
        foreach (var cond in conditions)
        {
            if (cond.Item1 < 0 || cond.Item1 > lst.Count - 1)
                return false;

            if (lst[cond.Item1] != cond.Item2)
                return false;
        }

        return true;
    }
}

如何在数组中的列表中搜索字符串？

5 个答案: