Custom Sort function does not work

Question

I have implemented a custom sort function for a list. But after calling it, the order of the list does not seem to change.

I want to find the largest number that comes from the combination of all numbers. eg, give 540, 9, it should output 9540 instead of 5409. So The compare function does the job.

    public void LargestPossibleNumberCombination(List<int> nums) {
        nums.Sort(CustomCompare);

    }
    public int CustomCompare(int x, int y)
    {
        string a = x +""+ y;
        string b = y + "" + x;
        return a.CompareTo(b) > 0 ? 0 : 1;
    }

Answer 1

You need to return a value when x is less than y (<0), when y is less than x (>0) and when are equals (0).

However you can make this sort more compact using a lambda comparison:

nums.Sort((x, y) => string.Compare(string.Format("{0}{1}", y, x), 
                                   string.Format("{0}{1}", x, y)));

If you want to join the list after being sorted:

var result = string.Join("", nums);