sorting issue icomparer

[safra]

Hi,

icomparer confuses me!

I have a class, very simple put:

public class myClass{
int[] ints1;
int[] ints2;
}

Now I have an array of myClass[] and would like to sort the array on ints[2].

Is that possible?

Thanks!

[RedBully]

Each class has an array of ints in it

e.g. myClass 1 could have an ints2 array of 1,2,3,4,5
e.g. myClass 2 could have an ints2 array of 1,2,3,4,5

In this case, when you sort your array of myClass, what should come first, myClass 1 or myClass2?

[safra]

That is an impossible situation considering how these arrays are build. But if it would be possible, then it doesn't really matter how this is handled.

[RedBully]

You need to inherit from IComparer or IComparer<myClass>

e.g.

public class myClass : IComparable<myClass>
{
        int[] ints1;
        int[] ints2;

        public int CompareTo(myClass other)
        {
            //Put in comparision between classes here.
            //Not sure what logic you actually want to implement
            //to decide if 'this' comes before or after 'other'?
            
            //I'm going to sort based on a comparision of the length
            //of the int2 array but you can change this to some other logic.
            return ints2.Length.CompareTo(other.ints2.Length)    
        }
}

[safra]

Thanks a lot RedBully!

I will try tomorrow, around midnight over here.

It has to sort on ints2 and then ideally a specific element I can pass, something like this?

public class myClass : IComparable<myClass>
{
        int[] ints1;
        int[] ints2;

        public int CompareTo(myClass other, int element)
        {
            //Put in comparision between classes here.
            //Not sure what logic you actually want to implement
            //to decide if 'this' comes before or after 'other'?
            
            //I'm going to sort based on a comparision of the length
            //of the int2 array but you can change this to some other logic.
            return ints2[element].CompareTo(other.ints2[element])    
        }
}

[RedBully]

Let me know how it goes.

I prefer to you use List<myClass> instead of myClass[] because list has the Sort method on it.

List<myClass> instances = new List<myClass>();
instances.Add(new myClass());
instances.Add(new myClass());

//Call sort on instances and it will use the sort logic
//defined by the CompareTo method in the myClass class.
instances.Sort();

Alternatively use Array.Sort(instances) if using a traditional array.
Both will use your CompareTo method.

You can also define multiple sort methods that can be passed to a sort method.

public class myClass : IComparable<myClass>
{
        int[] ints1;
        int[] ints2;

        public static int SpecialSort(myClass a, myClass b)
       {
              return a.ints1.Length.CompareTo(b.ints1.Length);
       {

        public int CompareTo(myClass other, int element)
        {
            //Put in comparision between classes here.
            //Not sure what logic you actually want to implement
            //to decide if 'this' comes before or after 'other'?
            
            //I'm going to sort based on a comparision of the length
            //of the int2 array but you can change this to some other logic.
            return ints2[element].CompareTo(other.ints2[element])    
        }
}

You can then use your special sorting methods for your sorting:

Array.Sort(instances, myClass.SpecialSort)