Csharp/CSharp Tutorial/Data Structure/Dictionary

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Add to dictionary

<source lang="csharp">using System; using System.Collections.Generic;

   public class Tester
   {
       static void Main()
       {
           Dictionary<string, string> Dictionary = new Dictionary<string, string>();
           Dictionary.Add("1", "J");
           Dictionary.Add("2", "S");
           Dictionary.Add("3", "D");
           Dictionary.Add("4", "A");
           Console.WriteLine(Dictionary["1"]);
       }
   }</source>

Dictionary Demo

<source lang="csharp">using System; using System.Collections.Generic; using System.ruponentModel; using System.Text.RegularExpressions;

   class DictionaryDemo
   {
       static Dictionary<string,int> CountWords(string text)
       {
           Dictionary<string,int> frequencies = new Dictionary<string,int>();
               
           string[] words = Regex.Split(text, @"\W+");
               
           foreach (string word in words)
           {
               if (frequencies.ContainsKey(word))
               {
                   frequencies[word]++;
               }
               else
               {
                   frequencies[word] = 1;
               }
           }
           return frequencies;
       }
       static void Main()
       {
           string text = "this is a test";
           Dictionary<string, int> frequencies = CountWords(text);
           foreach (KeyValuePair<string, int> entry in frequencies)
           {
               string word = entry.Key;
               int frequency = entry.Value;
               Console.WriteLine("{0}: {1}", word, frequency);
           }
       }
   }</source>

Use the keys to obtain the values from a generic Dictionary<TK, TV>

<source lang="csharp">using System; using System.Collections.Generic;

class MainClass {

 public static void Main() {  
   Dictionary<string, double> dict = new Dictionary<string, double>();  
     
   // Add elements to the collection. 
   dict.Add("A", 7);  
   dict.Add("B", 5);  
   dict.Add("C", 4);  
   dict.Add("D", 9);  
 
   // Get a collection of the keys (names). 
   ICollection<string> c = dict.Keys;  
 
   foreach(string str in c)  
     Console.WriteLine("{0}, Salary: {1:C}", str, dict[str]);  
 }  

}</source>

A, Salary: $7.00
B, Salary: $5.00
C, Salary: $4.00
D, Salary: $9.00