Method in C to find duplicate values in Dictionary

  • 2020-06-03 08:07:20
  • OfStack

Introduction to the

In this help document, I'll show you how to implement the lookup of repeated values in the dictionary in c#. You know this is very simple code for an old bird. Nevertheless, this is a very useful help document for beginners in c#.


The way most programmers deal with small data source stores is usually to create dictionaries for key-value stores. The primary key is only 1, but the dictionary value may have duplicate elements.


Here I use a simple LINQ statement to find duplicate values in the dictionary.

//initialize a dictionary with keys and values.    
Dictionary<int, string> plants = new Dictionary<int, string>() {    
    {1,"Speckled Alder"},    
    {2,"Apple of Sodom"},    
    {3,"Hairy Bittercress"},    
    {4,"Pennsylvania Blackberry"},    
    {5,"Apple of Sodom"},    
    {6,"Water Birch"},    
    {7,"Meadow Cabbage"},    
    {8,"Water Birch"}    

Response.Write("<b>dictionary elements........ </b><br />");

//loop dictionary all elements   
foreach (KeyValuePair<int, string> pair in plants)  
    Response.Write(pair.Key + "....."+ pair.Value+"<br />");

//find dictionary duplicate values.  
var duplicateValues = plants.GroupBy(x => x.Value).Where(x => x.Count() > 1);

Response.Write("<br /><b>dictionary duplicate values..........</b><br />");

//loop dictionary duplicate values only            
foreach(var item in duplicateValues)  
    Response.Write(item.Key+"<br />");

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