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  1. using System;
  2. using System.Collections;
  3. using System.Collections.Generic;
  4. using System.Linq;
  5.  
  6. class Foo {
  7. 	public static Type GetEnumerableType(Type type)
  8. 	{
  9. 	    if (type == null)
  10. 	        throw new ArgumentNullException("type");
  11.  
  12. 	    if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(IEnumerable<>))
  13. 	        return type.GetGenericArguments()[0];
  14.  
  15. 	    var iface = (from i in type.GetInterfaces()
  16. 	                 where i.IsGenericType && i.GetGenericTypeDefinition() == typeof(IEnumerable<>)
  17. 	                 select i).FirstOrDefault();
  18.  
  19. 	    if (iface == null)
  20. 	        throw new ArgumentException("Does not represent an enumerable type.", "type");
  21.  
  22. 	    return GetEnumerableType(iface);
  23. 	}
  24.  
  25. 	static void Main() {
  26. 	    foreach (var type in new[] {
  27. 	                 typeof(IEnumerable<string>),
  28. 	                 typeof(List<int>),
  29. 	                 typeof(EnumerableTest)
  30. 	             }) {
  31. 	    	Console.WriteLine("{0}: {1}",
  32. 	    		type.FullName,
  33. 	    		GetEnumerableType(type).FullName);
  34. 	    }
  35. 	}
  36. }
  37.  
  38. class EnumerableTest : IEnumerable<long>, IEnumerable<double> {
  39.     IEnumerator<long> IEnumerable<long>.GetEnumerator() {
  40.         throw new NotImplementedException();
  41.     }
  42.     IEnumerator<double> IEnumerable<double>.GetEnumerator() {
  43.         throw new NotImplementedException();
  44.     }
  45.     public IEnumerator GetEnumerator() {
  46.         throw new NotImplementedException();
  47.     }
  48. }
Success #stdin #stdout 0.02s 38032KB
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stdout
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System.Collections.Generic.IEnumerable`1[[System.String, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]: System.String
System.Collections.Generic.List`1[[System.Int32, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]: System.Int32
EnumerableTest: System.Int64
https://ideone.com/TUC31
language:
C# (gmcs 5.20.1)
created:
12 years ago
visibility:
secret

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