c# - How to create a List<int> basead on two properties from another list? -

problem

i need create list<int> basead on 2 properties list.

example

i have class has 2 fields need.

public class myclass {     //other fields     int? valueid     int? valuetwoid } 

above code it's example, not focus there.

i want retrieve properties like:

myclasslist.elementat(0).valueid = 1; myclasslist.elementat(0).valuetwoid = 2; myclasslist.elementat(1).valueid = 3; myclasslist.elementat(1).valuetwoid = 4;  list<int> resultlist = myclasslist.where(x => x.valueid != null && x.valuetwoid != null).select(x => ??).tolist()); 

desired output

resultlist.elementat(0) == 1 resultlist.elementat(1) == 2 resultlist.elementat(2) == 3 resultlist.elementat(3) == 4 

there's way achieve using .select(x => ).tolist(), without using code like:

list<int> resultlist = new list<int>();  foreach(var item in myclasslist) {    resultlist.add(item.valueid);    resultlist.add(item.valuetwoid); } 

thanks in advance, sorry poor english.

try

list<int> resultlist = myclasslist     .where(x => x.valueid != null && x.valuetwoid != null)     .selectmany(x => new list<int>{x.valueid.value, x.valuetwoid.value})     .tolist(); 

as in:

using system; using system.collections.generic; using system.linq;  namespace example {     internal class program     {         public static void main(string[] args)         {             var myclasslist = new list<myclass> {new myclass(), new myclass()};             myclasslist.elementat(0).valueid = 1;             myclasslist.elementat(0).valuetwoid = 2;             myclasslist.elementat(1).valueid = 3;             myclasslist.elementat(1).valuetwoid = 4;              var resultlist = myclasslist                 .where(x => x.valueid != null && x.valuetwoid != null)                 .selectmany(x => new list<int> { x.valueid.value, x.valuetwoid.value})                 .tolist();              foreach (var in resultlist)             {                 console.writeline(i);             }             //prints out:             //1             //2             //3             //4             console.readline();         }          public class myclass         {             public int? valueid;             public int? valuetwoid;         }     } }