C# | Check whether a SortedList object contains a specific key

Last Updated : 11 Jul, 2025
SortedList.Contains(Object) Method is used to check whether a SortedList object contains a specific key. Syntax: 
public virtual bool Contains (object key);
Here, key is the Key which is to be located in the SortedList object. Return Value: This method returns the true if the SortedList object contains an element with the specified key otherwise, it returns false Exceptions:
  • ArgumentNullException: If the key is null.
  • InvalidOperationException: If the comparer throws an exception.
Below programs illustrate the use of above-discussed method: Example 1: CSharp 
// C# code to Check whether a SortedList
// object contains a specific key
using System;
using System.Collections;

class Geeks {

    // Main Method
    public static void Main(String[] args)
    {

        // Creating a SortedList of integers
        SortedList mylist = new SortedList();

        // Adding elements to SortedList
        mylist.Add("1", "C++");
        mylist.Add("2", "Java");
        mylist.Add("3", "DSA");
        mylist.Add("4", "Python");
        mylist.Add("5", "C#");

        // Checking whether 4 is present
        // in SortedList or not
        Console.Write(mylist.Contains("4"));
    }
}
Output: 
True
Example 2: CSharp 
// C# code to Check whether a SortedList
// object contains a specific key
using System;
using System.Collections;

class Geeks {

    // Main Method
    public static void Main(String[] args)
    {

        // Creating a SortedList of integers
        SortedList mylist = new SortedList();

        // Adding elements to SortedList
        mylist.Add("First", "Ram");
        mylist.Add("Second", "Shyam");
        mylist.Add("Third", "Mohit");
        mylist.Add("Fourth", "Rohit");
        mylist.Add("Fifth", "Manish");

        // Checking whether 10 is present
        // in SortedList object or not
        Console.Write(mylist.Contains("Sixth"));
    }
}
Output: 
False
Note:
  • Contains implements IDictionary.Contains. It behaves exactly as ContainsKey.
  • This method uses a binary search algorithm; therefore, this method is an O(log n) operation, where n is Count.
Reference:
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