C# | Get an ICollection containing the keys in ListDictionary Last Updated : 11 Jul, 2025 Comments Improve Suggest changes Like Article Like Report ListDictionary.Keys property is used to get an ICollection containing the keys in the ListDictionary. Syntax: public System.Collections.ICollection Keys { get; } Return Value : It returns an ICollection containing the keys in the ListDictionary. Below are the programs to illustrate the use of ListDictionary.Keys property: Example 1: CSHARP // C# code to get an ICollection // containing the keys in the ListDictionary using System; using System.Collections; using System.Collections.Specialized; class GFG { // Driver code public static void Main() { // Creating a ListDictionary named myDict ListDictionary myDict = new ListDictionary(); myDict.Add("Australia", "Canberra"); myDict.Add("Belgium", "Brussels"); myDict.Add("Netherlands", "Amsterdam"); myDict.Add("China", "Beijing"); myDict.Add("Russia", "Moscow"); myDict.Add("India", "New Delhi"); // Get an ICollection containing // the keys in the ListDictionary ICollection ic = myDict.Keys; // Displaying the keys in ICollection ic foreach(String str in ic) { Console.WriteLine(str); } } } Output: Australia Belgium Netherlands China Russia India Example 2: CSHARP // C# code to get an ICollection // containing the keys in the ListDictionary using System; using System.Collections; using System.Collections.Specialized; class GFG { // Driver code public static void Main() { // Creating a ListDictionary named myDict ListDictionary myDict = new ListDictionary(); myDict.Add("I", "first"); myDict.Add("II", "second"); myDict.Add("III", "third"); myDict.Add("IV", "fourth"); myDict.Add("V", "fifth"); // Get an ICollection containing // the keys in the ListDictionary ICollection ic = myDict.Keys; // Displaying the keys in ICollection ic foreach(String str in ic) { Console.WriteLine(str); } } } Output: I II III IV V Note: The order of the values in the ICollection is unspecified, but it is the same order as the associated values in the ICollection returned by the Values method. The returned ICollection is not a static copy. Instead, the ICollection refers back to the keys in the original ListDictionary. Therefore, changes to the ListDictionary continue to be reflected in the ICollection. Retrieving the value of this property is an O(1) operation. Reference: https://learn.microsoft.com/en-us/dotnet/api/system.collections.specialized.listdictionary.keys?view=netframework-4.7.2 Comment S Sahil_Bansall Follow 0 Improve S Sahil_Bansall Follow 0 Improve Article Tags : C# CSharp-Specialized-Namespace CSharp-Specialized-ListDictionary Explore IntroductionC# Tutorial 2 min read Introduction to .NET Framework 6 min read C# .NET Framework (Basic Architecture and Component Stack) 6 min read C# Hello World 2 min read Common Language Runtime (CLR) in C# 4 min read FundamentalsC# Identifiers 2 min read Data Types in C# 6 min read C# Variables 4 min read C# Literals 5 min read Operators in C# 7 min read C# Keywords 5 min read Control StatementsC# Decision Making (if, if-else, if-else-if ladder, nested if, switch, nested switch) 5 min read C# Switch Statement 4 min read Loops in C# 4 min read C# Jump Statements (Break, Continue, Goto, Return and Throw) 4 min read OOP ConceptsClass and Objects in C# 4 min read Constructors in C# 5 min read C# Inheritance 3 min read Encapsulation in C# 2 min read C# Abstraction 4 min read MethodsMethods in C# 4 min read Method Overloading in C# 4 min read Method Parameters in C# 4 min read Method Overriding in C# 7 min read Anonymous Method in C# 2 min read ArraysArrays in C# 6 min read Jagged Arrays in C# 4 min read Array Class in C# 5 min read How to Sort an Array in C# | Array.Sort() Method Set - 1 8 min read How to find the rank of an array in C# 2 min read ArrayListArrayList in C# 6 min read ArrayList Class in C# 4 min read C# | Array vs ArrayList 2 min read StringStrings in C# 6 min read C# Verbatim String Literal - @ 5 min read C# String Class 9 min read C# StringBuilder 4 min read C# String vs StringBuilder 3 min read TupleC# Tuple 7 min read C# Tuple Class 3 min read C# ValueTuple 7 min read C# ValueTuple Struct 4 min read IndexersC# Indexers 5 min read C# Multidimensional Indexers 5 min read C# - Overloading of Indexers 3 min read Like