Compiler Error CS1579

foreach statement cannot operate on variables of type 'type1' because 'type2' does not contain a public definition for 'identifier'

To iterate through a collection using the foreach statement, the collection must meet the following requirements:

• It must be an interface, class or struct.

• It must include a public GetEnumerator method that returns a type.

• The return type must contain a public property named Current, and a public method named MoveNext.

• For more information, see How to: Access a Collection Class with foreach (C# Programming Guide).

Example

In this sample, foreach is not able to iterate through the collection because there is no publicGetEnumerator method in MyCollection.

The following sample generates CS1579.

// CS1579.cs
using System;
public class MyCollection 
{
   int[] items;
   public MyCollection() 
   {
      items = new int[5] {12, 44, 33, 2, 50};
   }

   // Delete the following line to resolve.
   MyEnumerator GetEnumerator()

   // Uncomment the following line to resolve:
   // public MyEnumerator GetEnumerator() 
   {
      return new MyEnumerator(this);
   }

   // Declare the enumerator class:
   public class MyEnumerator 
   {
      int nIndex;
      MyCollection collection;
      public MyEnumerator(MyCollection coll) 
      {
         collection = coll;
         nIndex = -1;
      }

      public bool MoveNext() 
      {
         nIndex++;
         return(nIndex < collection.items.GetLength(0));
      }

      public int Current 
      {
         get 
         {
            return(collection.items[nIndex]);
         }
      }
   }

   public static void Main() 
   {
      MyCollection col = new MyCollection();
      Console.WriteLine("Values in the collection are:");
      foreach (int i in col)   // CS1579
      {
         Console.WriteLine(i);
      }
   }
}