IEnumerable<T> Interface

Namespace: System.Collections.Generic
Assembly: System.Runtime

Represents a strongly typed collection that can be enumerated.

Summary

The IEnumerable<T> interface is the base interface for all generic collections in the .NET Framework. It is used to iterate over a collection, which is a collection of items that can be accessed by index or by iterating through the collection. The IEnumerable<T> interface exposes the GetEnumerator method, which returns an enumerator for the collection.

Interface Declaration

public interface IEnumerable<out T> : IEnumerable

Members

Methods

Name Description
IEnumerator<T> GetEnumerator() Returns an enumerator that iterates through the collection. The enumerator for a generic collection is typed to the type of elements in the collection.

Remarks

The IEnumerable<T> interface is the generic counterpart to the non-generic IEnumerable interface. Most of the collections in the .NET Framework implement IEnumerable<T>. LINQ queries are also based on IEnumerable<T>.

When you use a foreach loop to iterate over a collection that implements IEnumerable<T>, the compiler generates code that calls the GetEnumerator method to obtain an enumerator, and then repeatedly calls the MoveNext method on the enumerator to get the next element.

Examples

Iterating over a List

The following example demonstrates how to use a foreach loop to iterate over a List<string>, which implements IEnumerable<string>.

using System;
using System.Collections.Generic;

public class Example
{
    public static void Main(string[] args)
    {
        List<string> fruits = new List<string> { "Apple", "Banana", "Cherry" };

        // Iterating using foreach loop
        foreach (string fruit in fruits)
        {
            Console.WriteLine(fruit);
        }
    }
}

Using GetEnumerator directly

Although the foreach loop is the most common way to use IEnumerable<T>, you can also use the GetEnumerator method directly.

using System;
using System.Collections.Generic;

public class Example
{
    public static void Main(string[] args)
    {
        List<int> numbers = new List<int> { 1, 2, 3, 4, 5 };

        using (IEnumerator<int> enumerator = numbers.GetEnumerator())
        {
            while (enumerator.MoveNext())
            {
                int currentNumber = enumerator.Current;
                Console.WriteLine(currentNumber);
            }
        }
    }
}

See Also