ForEach loop not changing property of class

Question

I've seen a couple questions about this, and done some research. My understanding is that when you run a foreach on IEnumerable: if T is a Reference Type (e.g. Class) you should be able to modify properties of the object from within the loop. If T is a value type (e.g. Struct) this would not work since the iteration variable would be a local copy. I am working on a Windows Store app with the following code: My Class: ``` public class WebResult { public string Id { get; set; } public string Title { get; set; } public string Description { get; set; } public string DisplayUrl { get; set; } public string Url { get; set; } public string TileColor { get { string[] colorArray = { "FFA200FF", "FFFF0097", "FF00ABA9", "FF8CBF26", "FFA05000", "FFE671B8", "FFF09609", "FF1BA1E2", "FFE51400", "FF339933" }; Random random = new Random(); int num = random.Next(0, (colorArray.Length - 1)); return "#" + colorArray[num]; } } public string Keywords { get; set; } } ``` The Code: ``` IEnumerable<WebResult>…

Accepted Answer

This is known as `deferred execution`; `results` is a query that is executed every time you iterate over it. In your case it's evaluated twice, once in the for loop, and a second time when it's databound.

You can verify this by doing something like this

```
var results2 = results.ToList();

foreach (WebResult result in results2)
{
    result.Keywords = "These, are, my, keywords";
}

if (control is GridView)
{
    (control as GridView).ItemsSource = results2;
}
```

You should see that your changes persisted.

ForEach loop not changing property of class

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