How to sort an array of objects (classes)?

December 17, 2021

I’m trying to sort an array of objects with Array.Sort, but get an InvalidOperationException. As i have read i’m trying to sort a complex object and I need to use a IComparable <T> comparsion interface, but I don’t understand how it works.

There is my code:

     public class C
     {
         public int I { get; set; }
     }

     static void Main(string[] args)
     {
         C[] classes = new C[100000];
         Random rand = new Random();
         for (int i = 0; i < 100000; i++)
         {
            classes[i] = new C { I = rand.Next(1, 100000) };
         }
     
         Array.Sort<C>(classes); // Here I get an exception
     }

>Solution :

You should explain to .Net how to compare classes:

...
// having a and b instances we should compare I properties
Array.Sort<C>(classes, (a, b) => a.I.CompareTo(b.I)); 
...

Or you can make class C comparable (in order Array.Sort<C>(classes); to start working):

public class C : IComparable<C> {
  public int I { get; set; }

  public int CompareTo(C other) {
    if (null == other)
      return 1;

    return I.CompareTo(other.I);  
  }
}