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    <p>Here's a simple example:</p> <pre><code>public class SortableItem : IComparable&lt;SortableItem&gt; { public int someNumber; #region IComparable&lt;SortableItem&gt; Members public int CompareTo(SortableItem other) { int ret = -1; if (someNumber &lt; other.someNumber) ret = -1; else if (someNumber &gt; other.someNumber) ret = 1; else if (someNumber == other.someNumber) ret = 0; return ret; } #endregion } </code></pre> <p><em>"That's great, but what if I want to be able to control the sort order, or sort by another field?"</em></p> <p>Simple. All we need to do is add few more fields to the object. First we'll add a string for a different sort type and then we'll add a boolean to denote whether we're sorting in descending or ascending order and then add a field which determines which field we want to search by.</p> <pre><code>public class SortableItem : IComparable&lt;SortableItem&gt; { public enum SortFieldType { SortNumber, SortString } public int someNumber = -1; public string someString = ""; public bool descending = true; public SortFieldType sortField = SortableItem.SortFieldType.SortNumber; #region IComparable&lt;SortableItem&gt; Members public int CompareTo(SortableItem other) { int ret = -1; if(sortField == SortableItem.SortFieldType.SortString) { // A lot of other objects implement IComparable as well. // Take advantage of this. ret = someString.CompareTo(other.someString); } else { if (someNumber &lt; other.someNumber) ret = -1; else if (someNumber &gt; other.someNumber) ret = 1; else if (someNumber == other.someNumber) ret = 0; } // A quick way to switch sort order: // -1 becomes 1, 1 becomes -1, 0 stays the same. if(!descending) ret = ret * -1; return ret; } #endregion public override string ToString() { if(sortField == SortableItem.SortFieldType.SortString) return someString; else return someNumber.ToString(); } } </code></pre> <p><em>"Show me how!"</em></p> <p>Well since you asked so nicely.</p> <pre><code>static class Program { static void Main() { List&lt;SortableItem&gt; items = new List&lt;SortableItem&gt;(); SortableItem temp = new SortableItem(); temp.someString = "Hello"; temp.someNumber = 1; items.Add(temp); temp = new SortableItem(); temp.someString = "World"; temp.someNumber = 2; items.Add(temp); SortByString(items); Output(items); SortAscending(items); Output(items); SortByNumber(items); Output(items); SortDescending(items); Output(items); Console.ReadKey(); } public static void SortDescending(List&lt;SortableItem&gt; items) { foreach (SortableItem item in items) item.descending = true; } public static void SortAscending(List&lt;SortableItem&gt; items) { foreach (SortableItem item in items) item.descending = false; } public static void SortByNumber(List&lt;SortableItem&gt; items) { foreach (SortableItem item in items) item.sortField = SortableItem.SortFieldType.SortNumber; } public static void SortByString(List&lt;SortableItem&gt; items) { foreach (SortableItem item in items) item.sortField = SortableItem.SortFieldType.SortString; } public static void Output(List&lt;SortableItem&gt; items) { items.Sort(); for (int i = 0; i &lt; items.Count; i++) Console.WriteLine("Item " + i + ": " + items[i].ToString()); } } </code></pre>
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    1. POHow do I use the IComparable interface?
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    1. COThat is actually pretty yeucky, sorry to say it. There are much better approaches, especially using LINQ or a LINQ-inspired approach...
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    2. COThere isn't anything that says you can't answer the question too if you have a better idea.
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    3. COI have - I was just writing it ;-p
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