.NET Answers

Have you ever had a situation arise where you want to create a function that returns a collection of results and you want the results to be listed in a for each loop? 

Sure you have.  And I bet I know what your code looked like too:

public ArrayList CollectionFunction()
{
    ArrayList ar = new ArrayList();
    for (int i = 0; i < 10; i++)
    {
        ar.Add(i * (i + 1));
    }
    return ar;
}

public void CollectionEach()
{
    foreach (object o in CollectionFunction())
        Console.Write(o.ToString());
}

But did you know there is a much easier way to write this code and, as it turns out, it’s much more efficient too.

Instead of creating an array in the CollectionFunction() we can have CSharp take care of all the details by using the yield statement in our loop and making our CollectionFunction return IEnumerable instead of the ArrayList.

Here is the modified code:

public IEnumerable CollectionFunction()
{
    for (int i = 0; i < 10; i++)
    {
        yield return (i * (i + 1));
    }
}

public void CollectionEach()
{
    foreach (int i in CollectionFunction())
        Console.Write(i.ToString());
}

What happens under the hood is that a class is created to implement the behavior we’ve described in the code, meaning that the computation actually occurs AS we are looping through the IEnumerable object rather than building up a list, returning it, and then looping through the results.

Other Related Items:

12.8 oz. Sqwincher Liquid Concentrate (Yield 1 Gal) Lot of 20Model Number: 040305, 040302, 040304|UOM: CS |Properties: |(20) 12.8 oz Bottles per Case|Liquid Concentrate |Each Bottle Yields 1 Gallon|No Caffeine |... Read More >

Illustrated C# 2008 (Windows.Net)

The unique, visual format of Illustrated C# 2008 has been specially created by author, and teacher of development methods, Daniel Solis. The concis... Read More >

Bodum Pavina Double Wall Thermal Glass CollectionWith futuristic looks and high-tech construction, Bodum's Pavina drinkware makes an exciting departure from traditional glassmaking. Each vessel is cr... Read More >

If you're new here, you may want to subscribe to the mailing list to get notifications of new post and a virtual tour of past topics. Thanks for visiting!

Related Post

• Do you Need My Help?
• ASP.NET Dynamic Validator
• Upload a File via WebRequest Using CSharp
• ASP.NET Authentication – Multiple Domains w/ Same Application
• Embedding Google Search Appliance Results in ASP.NET

Bookmark to:

Hide Sites

2 Responses to “Advanced CSharp – yield”