IEnumerable

Maha

In this example IEnumerable interface is given a type 'int'. How to explain this situation?. Problem is highlighted.

using System;
using System.Collections.Generic;

class Program
{
static void Main()
{
List oyears = new List();
oyears.Add(1990);
oyears.Add(1991);
oyears.Add(1992);
oyears.Add(1993);
oyears.Add(2001);
oyears.Add(2002);
oyears.Add(2003);

IEnumerable ienum = (IEnumerable)oyears;

foreach (int i in ienum)
{
Console.WriteLine(i);
}

Console.ReadKey();
}
}

2 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes11y ago
Accepted answer
The generic type List implements the generic interface IEnumerable.

It therefore follows that List implements IEnumerable and so we can cast the List variable, oyears, to the IEnumerable type.

Moreover, we can then assign the result to the variable, ienum, which is also of the IEnumerable type.

In fact, you could have done this without a cast since there's always an implicit conversion between a type and an interface which it implements. So this would also work just as well:

using System;
using System.Collections.Generic;

class Program
{
static void Main()
{
List oyears = new List();
oyears.Add(1990);
oyears.Add(1991);
oyears.Add(1992);
oyears.Add(1993);
oyears.Add(2001);
oyears.Add(2002);
oyears.Add(2003);

IEnumerable ienum = oyears;

foreach (int i in ienum)
{
Console.WriteLine(i);
}

Console.ReadKey();
}
}
0
Maha11y ago
Thank you for your explanation.
0