How to find a key in a Dictionary with C#

How to find a key in a Dictionary with C#. The ContainsKey method checks if a key already exists in the dictionary.

Find a Key

The ContainsKey method checks if a key already exists in the dictionary. The following code snippet checks if a key already exits and if not, adds it.

  1. if (!AuthorList.ContainsKey("Mahesh Chand"))  
  2. {  
  3.     AuthorList["Mahesh Chand"] = 20;  
  4. }
Find a Value
 
The ContainsValue method checks if a value already exists in the dictionary. The following code snippet checks if a value already exits.
  1. if (!AuthorList.ContainsValue(9))  
  2. {  
  3.     Console.WriteLine("Item found");  

Sample
 
Here is the complete sample code showing how to use these methods.
  1. // Create a dictionary with string key and Int16 value pair  
  2. Dictionary<string, Int16> AuthorList = new Dictionary<string, Int16>();  
  3. AuthorList.Add("Mahesh Chand", 35);  
  4. AuthorList.Add("Mike Gold", 25);  
  5. AuthorList.Add("Praveen Kumar", 29);  
  6. AuthorList.Add("Raj Beniwal", 21);  
  7. AuthorList.Add("Dinesh Beniwal", 84);   
  8. // Count  
  9. Console.WriteLine("Count: {0}", AuthorList.Count);   
  10. // Set Item value  
  11. AuthorList["Neel Beniwal"] = 9;  
  12. if (!AuthorList.ContainsKey("Mahesh Chand"))  
  13. {  
  14.     AuthorList["Mahesh Chand"] = 20;  
  15. }  
  16. if (!AuthorList.ContainsValue(9))  
  17. {  
  18.     Console.WriteLine("Item found");  
  19. }  
  20. // Read all items  
  21. Console.WriteLine("Authors all items:");   
  22. foreach (KeyValuePair<string, Int16> author in AuthorList)  
  23. {  
  24.     Console.WriteLine("Key: {0}, Value: {1}",  
  25.         author.Key, author.Value);  
  26. }