Multiple parameters in a List How to create without a class

Question

This is probably a pretty obvious question  but how would I go about creating a List that has multiple parameters without creating a class   Example   var list   new List lt string  int gt      list Add  hello   1     I normally would use a class like so   public class MyClass       public String myString  get  set       public Int32 myInt32  get  set       then create my list by doing   var list   new List lt MyClass gt     list Add new MyClass   myString    hello   myInt32   1

User · Answer

If you do not mind the items being imutable you can use the Tuple class added to .net 4

var list = new List<Tuple<string,int>>();
list.Add(new Tuple<string,int>("hello", 1));

list[0].Item1 //Hello
list[0].Item2 //1

However if you are adding two items every time and one of them is unique id you can use a Dictionary

User · Answer

Another solution create generic list of anonymous type    var list   new           new   Number   10  Name    Smith         new   Number   10  Name    John        ToList      foreach  var item in list         Console WriteLine item Name        This also gives you intellisense support  I think in some situations its better than Tuple and Dictionary

User · Answer

List only accepts one type parameter  The closest you ll get with List is    var list   new List lt Tuple lt string  int gt  gt      list Add Tuple Create  hello   1

User · Answer

To add to what other suggested I like the following construct to avoid the annoyance of adding members to keyvaluepair collections   public class KeyValuePairList lt Tkey TValue gt    List lt KeyValuePair lt Tkey TValue gt  gt       public void Add Tkey key  TValue value           base Add new KeyValuePair lt Tkey  TValue gt  key  value              What this means is that the constructor can be initialized with better syntax    var myList   new KeyValuePairList lt int string gt   1  one    2  two    3  three       I personally like the above code over the more verbose examples Unfortunately C  does not really support tuple types natively so this little hack works wonders   If you find yourself really needing more than 2  I suggest creating abstractions against the tuple type  although Tuple is a class not a struct like KeyValuePair this is an interesting distinction    Curiously enough  the initializer list syntax is available on any IEnumerable and it allows you to use any Add method  even those not actually enumerable by your object  It s pretty handy to allow things like adding an  object   member as a  params object   member

User · Answer

Get Schema Name and Table Name from a database            public IList lt Tuple lt string  string gt  gt  ListTables                          DataTable dt   con GetSchema  Tables                 var tables   new List lt Tuple lt string  string gt  gt                  foreach  DataRow row in dt Rows                            string schemaName    string row 1               string tableName    string row 2                 AddToList                tables Add Tuple Create schemaName  tableName                Console WriteLine schemaName        tableName                              return tables

User · Answer

If appropriate  you might use a Dictionary which is also a generic collection   Dictionary lt string  int gt  d   new Dictionary lt string  int gt     d Add  string   1

User · Answer

As said by Scott Chamberlain and several others   Tuples work best if you don t mind having immutable ie read-only  objects   If  like suggested by David  you want to reference the int by the string value  for example  you should use a dictionary  Dictionary lt string  int gt  d   new Dictionary lt string  int gt     d Add  string   1   Console WriteLine d  string      prints 1   If  however  you want to store your elements mutably in a list  and don t want to use a dictionary-style referencing system  then your best bet ie only real solution right now  would be to use KeyValuePair  which is essentially std  pair for C    var kvp new KeyValuePair lt int  string gt  2   a      kvp Key 2 and a Value  a   kvp Key   3   both key and kvp Value    b    value are mutable   Of course  this is stackable  so if you need a larger tuple like if you needed 4 elements  you just stack it  Granted this gets ugly really fast        var quad new KeyValuePair lt KeyValuePair lt int string gt   KeyValuePair lt int string gt  gt                   new KeyValuePair lt int string gt  3  a                    new KeyValuePair lt int string gt  4  b       quad Key Key 3   So obviously if you were to do this  you should probably also define an auxiliary function   My advice is that if your tuple contains more than 2 elements  define your own class  You could use a typedef-esque using statement like    using quad   KeyValuePair lt KeyValuePair lt int string gt   KeyValuePair lt int string gt  gt     but that doesn t make your instantiations any easier  You d probably spend a lot less time writing template parameters and more time on the non-boilerplate code if you go with a user-defined class when working with tuples of more than 2 elements

User · Answer

For those wanting to use a Class   Create a Class with all the parameters you want  Create a list with the class as parameter       x000D   x000D  class MyClass x000D            x000D              public string S1  x000D              public string S2  x000D            x000D   x000D  List lt MyClass gt  MyList  new List lt MyClass gt     x000D   x000D   x000D

User · Answer

This works fine with me   List lt string gt  myList   new List lt string gt     myList Add string Format   0   1    hello   1       label myList 0  split      0   val   myList 0  split      1

User · Answer

If you are using  NET 4 0 you can use a Tuple   List lt Tuple lt T1  T2 gt  gt  list    For older versions of  NET you have to create a custom class  unless you are lucky enough to be able to find a class that fits your needs in the base class library

[c#] Multiple parameters in a List. How to create without a class?

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