What's the most elegant way to bubble-sort in C#?

Question

Can this be cleaned up?

using System;  
class AscendingBubbleSort 
{     
    public static void Main()
    {
        int i = 0,j = 0,t = 0;
        int []c=new int[20];
        for(i=0;i<20;i++)
        {
            Console.WriteLine("Enter Value p[{0}]:", i);
            c[i]=int.Parse(Console.ReadLine());
        }
        // Sorting: Bubble Sort
        for(i=0;i<20;i++)
        {
            for(j=i+1;j<20;j++)
            {
                if(c[i]>c[j])
                {
                    Console.WriteLine("c[{0}]={1}, c[{2}]={3}", i, c[i], j, c[j]);
                    t=c[i];
                    c[i]=c[j];
                    c[j]=t;
                }
            }
        }
        Console.WriteLine("bubble sorted array:");
        // sorted array output
        for(i=0;i<20;i++)
        {
            Console.WriteLine ("c[{0}]={1}", i, c[i]);
        }
    }
}

Answer 1

What you've pasted there isn't a bubble sort. It's a sort of "brute force" sort but it's not bubble sort. Here's an example of a generic bubble sort. It uses an arbitrary comparer, but lets you omit it in which case the default comparer is used for the relevant type. It will sort any (non-readonly) implementation of IList<T>, which includes arrays. Read the above link (to Wikipedia) to get more of an idea of how bubble sort is meant to work. Note how on each loop we go through from start to finish, but only compare each item with its neighbour. It's still an O(n²) sort algorithm, but in many cases it will be quicker than the version you've given.

public void BubbleSort<T>(IList<T> list)
{
    BubbleSort<T>(list, Comparer<T>.Default);
}

public void BubbleSort<T>(IList<T> list, IComparer<T> comparer)
{
    bool stillGoing = true;
    while (stillGoing)
    {
        stillGoing = false;
        for (int i = 0; i < list.Count-1; i++)
        {
            T x = list[i];
            T y = list[i + 1];
            if (comparer.Compare(x, y) > 0)
            {
                list[i] = y;
                list[i + 1] = x;
                stillGoing = true;
            }
        }
    }
}