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Looking up items in HashTable/Dictionary objects that have multiple keys

, 1 May 2008
Dictionary objects take a single key as a look up key. This class simplifies using a Dictionary when you have multiple keys, such as two strings and an int, etc.
classkeydemo.zip
ClassKeyDemo
ClassKeyDemo
bin
Debug
ClassKeyDemo.dll
Properties
Test
bin
Debug
ClassKeyDemo.dll
nunit.framework.dll
Test.dll
Properties
classkeydemoallmethods.zip
ClassKeyDemo.dll
ClassKeyDemo.dll
Test.dll
classkeydemoallmethodswithtuple.zip
ClassKeyDemoAllmethods
ClassKeyDemo
ClassKeyDemo
bin
Debug
ClassKeyDemo.dll
ClassKeyDemo.csproj.user
Properties
Test
bin
Debug
ClassKeyDemo.dll
Test.dll
Properties
Test.csproj.user
classkeydemowithstruct.zip
ClassKeyDemo.dll
ClassKeyDemo.dll
Test.dll
using System;
using System.Collections.Generic;
using System.Text;

using NUnit.Framework;
using Utility;
using System.Diagnostics;

namespace Testing
{
    [TestFixture]
    public class TestDictionaryOnly
    {
        /// <summary>
        /// Define test class to use key for
        /// </summary>
        public class TestClass
        {
            public string Column1 = null;
            public string Column2 = null;

            public TestClass(string Column1, string Column2)
            {
                this.Column1 = Column1;
                this.Column2 = Column2;
            }
        }

        //null keys are a problem that would have to be thought about on every usage
        //dictionary objects need to be created for each additional key

        public class PerfResults { public long initMS; public long lookupMS; }

        public PerfResults GetTestPerf()
        {
            Dictionary<string, Dictionary<string, TestClass>> testLookups = new Dictionary<string, Dictionary<string, TestClass>>();
            Stopwatch stopWatch = new Stopwatch();
            PerfResults results = new PerfResults();

            //test initialization
            stopWatch.Start();
            for (int i = 0; i < 1000000; i++)
            {
                TestClass testClass = new TestClass("Column1-" + i, "Column2-" + i);
                Dictionary<string, TestClass> lookupItem = new Dictionary<string,TestClass>();
                lookupItem.Add(testClass.Column2, testClass);
                testLookups.Add(testClass.Column1, lookupItem);
            }
            stopWatch.Stop();

            results.initMS = stopWatch.ElapsedMilliseconds;

            //test getting
            stopWatch = new Stopwatch();
            stopWatch.Start();
            for (int i = 0; i < 1000000; i++)
            {
                TestClass testClass = new TestClass("Column1-" + i, "Column2-" + i);
                
                //convenient syntax to just get, but if we want to do a containskey it is a pain
                //unless we do below and catch exception - nasty
                //TestClass lookupItem = testLookups[testClass.Column1][testClass.Column2];

                //using containskey to keep similar to tests for other methods
                //this get sfunky fast as more keys are used
                if (testLookups.ContainsKey(testClass.Column1))
                {
                    if (!testLookups[testClass.Column1].ContainsKey(testClass.Column2))
                        throw new ArgumentException("Can't find object we know is there");
                }
                else
                {
                    throw new ArgumentException("Can't find object we know is there");
                }
            }
            stopWatch.Stop();

            results.lookupMS = stopWatch.ElapsedMilliseconds;

            return results;
        }

        [Test]
        public void TestPerf()
        {
            int testRuns = 10;
            PerfResults totalResults = new PerfResults();

            for (int i = 0; i < testRuns; i++)
            {
                PerfResults thisResult = GetTestPerf();
                totalResults.initMS += thisResult.initMS;
                totalResults.lookupMS += thisResult.lookupMS;
            }

            Debug.WriteLine("Initialization: " + (totalResults.initMS / testRuns).ToString("N0") + "ms");
            Debug.WriteLine("Lookups: " + (totalResults.lookupMS / testRuns).ToString("N0") + "ms");
        }


    }
}

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About the Author

Paul B.

United States United States
I've been a software developer since 1996 and have enjoyed C# since 2003. I have a Bachelor's degree in Computer Science and for some reason, a Master's degree in Business Administration. I currently do software development contracting/consulting.

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