Question

I have a string array like this:

string[] names = new string[] { "john", "paul", "ringo", "george", "janis" };

I want to sort this array using a custom criteria. It can’t be alphabetical. It might be in this order: pgrj.

I’ve tried to implement a new IComparer, but inside the Compare() method I can’t use string.Compare cause it would sort alphabetically and I don’t want to do that.

The question is: How can I sort the names array in this order: pgrj ? In the ‘j’ case. Janis might be before John.

Thanks.

Answer 1

I would make an array of the letters of the alphabet, in the order that they should be sorted. Let’s call this array sort. You could then do something like

for (int i = 0; i < s1.Length; i++)
{
    int s1Value = sort.IndexOf(s1[i]);
    int s2Value = sort.IndexOf(s2[i]);

   if(s1Value > s2Value)
       return 1;

   if(s2Value > s1Value)
       return -1;
}

return 0;

Now a few disclaimers.

1. I might have my -1 and 1 mixed up. I haven’t looked at ICompare in a while and I forget which is which.
2. This does not handle the two strings being different lengths.
3. I have not tested this code.

You could improve on this by making a custom class to assign a weight to each character.

class CustomAlphabetSort
{
     public char Character { get; set; }
     public int Weight { get; set; }
}

From here you can sum of the value for each letter of a string and do the comparison that way. It might be a little more complex than your situation requires