CODEWITHSUNDEEP
c#.netasp.netsortingarraylist
Ram
Ram

Reputation: 933

How to sort ArrayList(int)

How can I sort the Arraylist in ascending and descending orders. Example.

ArrayList list= new ArrayList();
list.Add(2);
list.Add(8);
list.Add(0);
list.Add(1);

How can I sort the above list in both ascending and descending order?

Upvotes: 2

Views: 19140

Answers (8)

summerstar
summerstar

Reputation: 1

    private void DisplayMain()
    {
        string sValue = "1,2,5,8,6,7,110,220";
        txtValue.Text = sValue;
        string[] asDS = sValue.Split(',');
        ArrayList alData = new ArrayList();
        foreach (string sDS in asDS)
        {
            alData.Add(sDS);
        }//end of foreach
        alData.Sort(new IntSort());
        //============
        int iCnt = 0;
        StringBuilder sbResult = new StringBuilder();
        foreach (string sData in alData)
        {
            iCnt++;
            sbResult.AppendLine(iCnt.ToString() + " ====> " + sData);
        }//end of if 
        string sResult = sbResult.ToString();
        txtResult.Text = sResult;
    }//end of DisplayMain

    public class IntSort : IComparer
    {
        public int Compare(object x, object y)
        {
            string sX = x.ToString();
            string sY = y.ToString();
            int iResult = 0;
            int iX = int.Parse(sX);
            int iY = int.Parse(sY);
            if(iX > iY) { iResult = 1; }//end of if
            else if (iY > iX) { iResult = -1; }//end of if 
            return iResult;
            //return ((int)y).CompareTo((int)x);
        }
    }

Upvotes: 0

Vince Figueroa
Vince Figueroa

Reputation: 11

With the ascending list, you can use list.Sort()

And the for the descending list, there's an easy way to do it!

You can do descending lists like this:

list.Sort();
list.Reverse();

Upvotes: 0

Abel
Abel

Reputation: 57159

You can use list.Sort() for ascending order. For descending order, you need to reverse the order by implementing IComparer. Something like this will do:

// calling normal sort:
ArrayList ascendingList = list.Sort();

// calling reverse sort:
ArrayList descendingList = list.Sort(new ReverseSort());

// implementation:
public class ReverseSort : IComparer
{
    public int Compare(object x, object y)
    {
        // reverse the arguments
        return Comparer.Default.Compare(y, x);
    }

}

Note that, like Jon Skeet mentions in the comment thread under the main question, you do not need to use the untyped ArrayList at all. Instead, you can use the generic List<T>, which is typesafe and is simply more versatile.

Upvotes: 2

Xiphos
Xiphos

Reputation: 338

list.Sort() will sort them but I would suggest using List<> and Collections for sorting. Avoid using ArrayList imo.

Upvotes: 0

Mark Schadler
Mark Schadler

Reputation: 126

ArrayList contains a Sort method. (Edited to remove incorrect .NET information)

Upvotes: 1

Jay
Jay

Reputation: 6294

Using an array list instead of List<int> here is dangerous, however, here is what you are looking for:

System.Collections.ArrayList al = new System.Collections.ArrayList();
al.Add(5);
al.Add(3);
al.Add(1);
al.Add(4);
al.Add(0);
al.Sort();

foreach (var x in al)
{
    Console.WriteLine(x.ToString());
}

al.Sort(new DescendingIntSorter());

foreach (var x in al)
{
    Console.WriteLine(x.ToString());
}



public class DescendingIntSorter : System.Collections.IComparer
{
    public int Compare(object x, object y)
    {
        return ((int)y).CompareTo((int)x);
    }
}

Upvotes: 0

Muhammad Akhtar
Muhammad Akhtar

Reputation: 52241

You can you use ArrayList.Sort Method

Upvotes: 1

Yara
Yara

Reputation: 4565

You can use list.Sort() function. see example here http://msdn.microsoft.com/ru-ru/library/0e743hdt.aspx

Upvotes: 1

Related Questions