You can use the yield keyword in a method to implement an iterator. The method in which it is defined returns an IEnumerable or IEnumerator. The resulting iterator can be consumed using the foreach statement.
Below is an example of a method that returns an IEnumerable<T> which can then be iterated upon using a foreach statement.
static IEnumerable<Dog> DogsWithKids(IEnumerable<Dog> dogList)
{
foreach (Dog d in dogList)
{
yield return d;
yield return new Dog(d.Name + " Jr.",
Math.Max(d.Age - 3, 1));
}
}
static void Main(string[] args)
{
List<Dog> myDogs = new List<Dog>
{
new Dog {Name = "Kirby", Age = 15},
new Dog {Name = "Ruby", Age = 2}
};
// Iterate through dogs w/offsprings
foreach (Dog d in DogsWithKids(myDogs))
Console.WriteLine(d);
Console.ReadLine();
}
The result is a sequence with twice as many elements as the original List<T>.
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Filed under: Collections Tagged: C#, Collections, foreach, Iterator, yield Image may be NSFW.
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