C# 定义一个像 List<int,string> 这样的列表？
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define a List like List<int,string>?
提问by Benny Ae
I need a two column list like:
我需要一个两列列表，如：
List<int,string> mylist= new List<int,string>();
it says
它说
using the generic type
System.collection.generic.List<T>requires 1 type arguments.
使用泛型
System.collection.generic.List<T>需要 1 个类型参数。
采纳答案by James
You could use an immutablestruct
您可以使用不可变结构
public struct Data
{
public Data(int intValue, string strValue)
{
IntegerData = intValue;
StringData = strValue;
}
public int IntegerData { get; private set; }
public string StringData { get; private set; }
}
var list = new List<Data>();
Or a KeyValuePair<int, string>
或者一个 KeyValuePair<int, string>
using Data = System.Collections.Generic.KeyValuePair<int, string>
...
var list = new List<Data>();
list.Add(new Data(12345, "56789"));
回答by newfurniturey
Depending on your needs, you have a few options here.
根据您的需要，您在此处有几个选择。
If you don't need to do key/value lookups and want to stick with a List<>, you can make use of Tuple<int, string>:
如果您不需要进行键/值查找并想坚持使用 a List<>，则可以使用Tuple<int, string>：
List<Tuple<int, string>> mylist = new List<Tuple<int, string>>();
// add an item
mylist.Add(new Tuple<int, string>(someInt, someString));
If you dowant key/value lookups, you could move towards a Dictionary<int, string>:
如果您确实想要键/值查找，您可以转向Dictionary<int, string>：
Dictionary<int, string> mydict = new Dictionary<int, string>();
// add an item
mydict.Add(someInt, someString);
回答by walther
Not sure about your specific scenario, but you have three options:
不确定您的具体情况，但您有三个选择：
1.) use Dictionary<..,..>
2.) create a wrapper class around your values and then you can use List
3.) use Tuple
1.) 使用 Dictionary<..,..>
2.) 围绕您的值创建一个包装类，然后您可以使用 List
3.) 使用 Tuple
回答by andleer
Since your example uses a generic List, I assume you don't need an index or unique constraint on your data. A Listmay contain duplicate values. If you want to insure a unique key, consider using a Dictionary<TKey, TValue>().
由于您的示例使用 generic List，我假设您不需要对数据的索引或唯一约束。AList可能包含重复值。如果要确保唯一键，请考虑使用Dictionary<TKey, TValue>().
var list = new List<Tuple<int,string>>();
list.Add(Tuple.Create(1, "Andy"));
list.Add(Tuple.Create(1, "John"));
list.Add(Tuple.Create(3, "Sally"));
foreach (var item in list)
{
Console.WriteLine(item.Item1.ToString());
Console.WriteLine(item.Item2);
}
回答by Samuel Ptheitroadier
For that, you could use a Dictionarywhere the intis the key.
为此，您可以使用Dictionarywhereint是关键。
new Dictionary<int, string>();
If you really want to use a list, it could be a List<Tuple<int,string>>()but, Tupleclass is readonly, so you have to recreate the instance to modifie it.
如果你真的想使用一个列表，它可能是一个List<Tuple<int,string>>()但是，Tuple类是只读的，所以你必须重新创建实例来修改它。
回答by Navib
Use C# Dictionary datastructure it good for you...
使用 C# 字典数据结构对你有好处......
Dictionary<string, int> dict = new Dictionary<string, int>();
dict.Add("one", 1);
dict.Add("two", 2);
You can retrieve data from Ditionary in a simple way..
您可以通过一种简单的方式从 Ditionary 中检索数据。
foreach (KeyValuePair<string, int> pair in dict)
{
MessageBox.Show(pair.Key.ToString ()+ " - " + pair.Value.ToString () );
}
For more example using C# Dictionary... C# Dictionary
有关使用 C# 字典的更多示例... C# 字典
Navi.
导航。
回答by Hobelschlunze
List<Tuple<string, DateTime, string>> mylist = new List<Tuple<string, DateTime,string>>();
mylist.Add(new Tuple<string, DateTime, string>(Datei_Info.Dateiname, Datei_Info.Datum, Datei_Info.Gr??e));
for (int i = 0; i < mylist.Count; i++)
{
Console.WriteLine(mylist[i]);
}
回答by Magnetron
With the new ValueTuplefrom C# 7 (VS 2017 and above), there is a new solution:
使用ValueTupleC# 7的新版本（VS 2017 及更高版本），有一个新的解决方案：
List<(int,string)> mylist= new List<(int,string)>();
Which creates a list of ValueTuple type. If you're targeting .Net Framework 4.7+ or .Net Core, it's native, otherwise you have to get the ValueTuple package from nuget.
它创建了一个 ValueTuple 类型的列表。如果您的目标是 .Net Framework 4.7+ 或 .Net Core，则它是本机的，否则您必须从 nuget获取ValueTuple 包。
It's a struct opposing to Tuple, which is a class. It also has the advantage over the Tupleclass that you could create a named tuple, like this:
它是一个与 相对的结构体Tuple，它是一个类。与Tuple类相比，它还具有可以创建命名元组的优势，如下所示：
var mylist = new List<(int myInt, string myString)>();
That way you can access like mylist[0].myIntand mylist[0].myString
这样你就可以访问像mylist[0].myInt和mylist[0].myString
