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C# Sort KeyValuePair ListSort KeyValuePair structs in a List with CompareTo. Use a Comparison delegate.
Sort KeyValuePair List. A List contains many KeyValuePair struct instances. It can be sorted with the Sort List method. For advanced sorting, we need Comparison.
Comparison info. This code requires Comparison delegate implementations. We implement these as static int methods that call CompareTo.
Comparison
CompareTo
Sort
Example code. Compare1 receives two KeyValuePair structs and returns the result of CompareTo on their Key. Compare2 returns the CompareTo of the Value.
KeyValuePair
Main A new List of KeyValuePair instances is created. Three KeyValuePairs are created and added to the List.
Next The List is sorted with Compare1. The method target Compare1 is accepted as a Comparison delegate.
Then After printing the List, we sort it again with Compare2, and finally display the List again.
List
Console
using System; using System.Collections.Generic; class Program { static int Compare1(KeyValuePair<string, int> a, KeyValuePair<string, int> b) { return a.Key.CompareTo(b.Key); } static int Compare2(KeyValuePair<string, int> a, KeyValuePair<string, int> b) { return a.Value.CompareTo(b.Value); } static void Main() { var list = new List<KeyValuePair<string, int>>(); list.Add(new KeyValuePair<string, int>("Perl", 7)); list.Add(new KeyValuePair<string, int>("Net", 9)); list.Add(new KeyValuePair<string, int>("Dot", 8)); // Use Compare1 as comparison delegate. list.Sort(Compare1); foreach (var pair in list) { Console.WriteLine(pair); } Console.WriteLine(); // Use Compare2 as comparison delegate. list.Sort(Compare2); foreach (var pair in list) { Console.WriteLine(pair); } } }
[Dot, 8] [Net, 9] [Perl, 7] [Perl, 7] [Dot, 8] [Net, 9]
Program results. The List.Sort(Compare1) call sorts the List by the Key of the KeyValuePair. And the List.Sort(Compare2) call sorts the List by the Value int.
Sort List
Sorting info:
Compare1 -> Key Compare2 -> Value
A summary. We sorted collections of KeyValuePairs. We can use other syntax forms and implementations, such as LINQ expressions or lambda expressions, to accomplish this task.
orderby
Lambda
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Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.
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