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dirtylarry
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search hashtable by value, not by key?

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is there a way to search a hashtable by value, not by key in c#?

hashtable
  • asked one year ago
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last answered one year ago

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If you just want to check whether a particular value exists in the Hashtable, you can use the ContainsValue() method.

If you want to get the corresponding key (or keys) for a particular value, then the easiest way (if you're using .NET 3.5 or 4.0) is to use a LINQ query.

Here's a simple example:

using System;
using System.Collections;
using System.Linq;

class Test
{
   static void Main()
   {
      Hashtable creatures = new Hashtable();
      creatures.Add("lion", "mammal");
      creatures.Add("spider", "insect");
      creatures.Add("dog", "mammal");
      creatures.Add("eagle", "bird");

      if (creatures.ContainsValue("insect"))
      {
         Console.WriteLine("Creatures contains an insect");
      }

      // look for mammals

      var query = from DictionaryEntry de in creatures where (string)de.Value == "mammal" select de;

      foreach(DictionaryEntry de in query)
      {
         Console.WriteLine("{0} is a mammal", de.Key);
      }
   
      Console.ReadKey();
   }
}

  • answered one year ago by:

    vulpes
    17279
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dirtylarry
237

vulpes, you're the f'king man.

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