What are key-based I/O collections in C#?

The key-based I/O Collections in C# is what we call a SortedList −

SortedList<TKey,TValue>

The SortedList class represents a collection of key-and-value pairs that are sorted by the keys and are accessible by key and by index. This is how both of them gets added in a SortedList −

s.Add("Sub1", "Physics"); s.Add("Sub2", "Chemistry"); s.Add("Sub3", "Biology"); s.Add("Sub4", "Java");

The following is an example displaying the keys and values in a SortedList −

Example

 Live Demo

using System; using System.Collections; namespace Demo {    class Program {       static void Main(string[] args) {          SortedList s = new SortedList();          s.Add("Sub1", "Economics");          s.Add("Sub2", "Accountancy");          s.Add("Sub3", "Business Studies");          s.Add("Sub4", "English");          Console.WriteLine("Capacity = " + s.Capacity);          // get a collection of the keys.          ICollection key = s.Keys;          foreach (string k in key) {             Console.WriteLine(k + ": " + s[k]);          }       }    } }

Output

Capacity = 16 Sub1: Economics Sub2: Accountancy Sub3: Business Studies Sub4: English