C# | Check the HybridDictionary for a specific key

HybridDictionary.Contains(Object) method is used to determine whether the HybridDictionary contains a specific key or not.

Syntax:

public bool Contains (object key);

Here, key is the key to locate in the HybridDictionary.

Return Value: This method will return True if the HybridDictionary contains an entry with the specified key, otherwise, False.

Exception: The method throws ArgumentNullException if the key is null.

Below are the programs to illustrate the use of HybridDictionary.Contains(Object) method:

Example 1:

// C# code to check whether the 
// HybridDictionary contains a specific key. 
using System; 
using System.Collections; 
using System.Collections.Specialized; 
  
class GFG { 
  
    // Driver code 
    public static void Main() 
    { 
  
        // Creating a HybridDictionary named myDict 
        HybridDictionary myDict = new HybridDictionary(); 
  
        // Adding key/value pairs in myDict 
        myDict.Add("A", "Apple"); 
        myDict.Add("B", "Banana"); 
        myDict.Add("C", "Cat"); 
        myDict.Add("D", "Dog"); 
        myDict.Add("E", "Elephant"); 
        myDict.Add("F", "Fish"); 
  
        // To check whether the HybridDictionary 
        // contains "G". 
        Console.WriteLine(myDict.Contains("G")); 
  
        // To check whether the HybridDictionary 
        // contains "B". 
        Console.WriteLine(myDict.Contains("B")); 
    } 
} 

Output:

False
True

Example 2:

// C# code to check whether the 
// HybridDictionary contains a specific key. 
using System; 
using System.Collections; 
using System.Collections.Specialized; 
  
class GFG { 
  
    // Driver code 
    public static void Main() 
    { 
  
        // Creating a HybridDictionary named myDict 
        HybridDictionary myDict = new HybridDictionary(); 
  
        // Adding key/value pairs in myDict 
        myDict.Add("I", "first"); 
        myDict.Add("II", "second"); 
        myDict.Add("III", "third"); 
        myDict.Add("IV", "fourth"); 
        myDict.Add("V", "fifth"); 
  
        // To check whether the HybridDictionary 
        // contains "null". This should raise 
        // "ArgumentNullException" as key is null 
        Console.WriteLine(myDict.Contains(null)); 
    } 
} 

Runtime Error:

Unhandled Exception:
System.ArgumentNullException: Key cannot be null.
Parameter name: key

Note: This method is an O(1) operation.

Reference:

https://docs.microsoft.com/en-us/dotnet/api/system.collections.specialized.hybriddictionary.contains?view=netframework-4.7.2

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