Sorting a list by the third element

Devlin · March 11th, 2008, 01:57 PM

Ok, I have this posted in the C# 2005, but I realized that the studio I'm using is the newest, while the book is 2005 :D

This is running as a console app, not a win app.
I'm reading in a CSV file containing 5 elements per line into a list of objects, and I want to sort on the third element of the line. So, if the CSV line is this:

34919, 12, 0444, 20, Some Text

I want to sort on 0444. Currently it's not doing it.

Here's my code:

Code:

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace prgOne
{
    public class csvLineComparer : IComparer
    {
        public static IComparer Default = new csvLineComparer();
        public int Compare(object x, object y)
        {
            if (x is csvLine && y is csvLine)
            {
                return Comparer.Default.Compare(((csvLine)x).clNumb, ((csvLine)y).clNumb);
            }
            else
            {
                throw new ArgumentException("One or both objects to compare are not csvLine objects.");
            }
        }
    }
}

Code:

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace prgOne
{
    class csvLine : IComparable
    {
        public string clTime;
        public string clChan;
        public int clNumb;
        public string clStat;
        public string clDesc;

        public csvLine(string cltime, string clchan, int clnumb, string clstat, string cldesc)
        {
            clTime = cltime;
            clChan = clchan;
            clNumb = clnumb;
            clStat = clstat;
            clDesc = cldesc;
        }

        public int CompareTo(object obj)
        {
            if (obj is csvLine)
            {
                csvLine otherLine = obj as csvLine;
                return this.clNumb - otherLine.clNumb;
            }
            else
            {
                throw new ArgumentException("Object to compare is not a line.");
            }
        }
    }
}

Code:

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace prgOne
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] strArray;
            string strLine;
            char[] charArray = new char[] { ',' };

            FileStream aFile = new FileStream("C:\\csharp\\diag.log", FileMode.Open);
            StreamReader sr = new StreamReader(aFile);
            ArrayList lines = new ArrayList();

            strLine = sr.ReadLine();
            while (strLine != null)
            {
                strArray = strLine.Split(charArray);
                lines.Add(new csvLine(strArray[0], strArray[1], Convert.ToInt16(strArray[2]), strArray[3], strArray[4]));

                strLine = sr.ReadLine();
            }

            sr.Close();

            for (int i = 0; i < lines.Count; i++)
            {
                Console.WriteLine("{0}, {1}, {2}, {3}, {4}", (lines[i] as csvLine).clTime, (lines[i] as csvLine).clChan, (lines[i] as csvLine).clNumb, (lines[i] as csvLine).clStat, (lines[i] as csvLine).clDesc);
            }

            Console.ReadKey();
        }

    }
}

samjudson · March 11th, 2008, 02:06 PM

a) If you're going to post two forums, or rather 'move' forums, then try to tell the people on the other forum thats what you're doing.

b) You're not sorting your list...

lines.Sort();

c) Instead of using ArrayList(), just use List<csvLine>()

/- Sam Judson : Wrox Technical Editor -/

Devlin · March 11th, 2008, 02:50 PM

Quote:

quote:Originally posted by samjudson
a) If you're going to post two forums, or rather 'move' forums, then try to tell the people on the other forum thats what you're doing.

b) You're not sorting your list...

lines.Sort();

c) Instead of using ArrayList(), just use List<csvLine>()

/- Sam Judson : Wrox Technical Editor -/

A - Got it. Apologies.
B - I must have deleted it when I was editing somewhere, it was in there originally.
C - List lines = new List<csvLines> ?

John

Devlin · March 11th, 2008, 02:54 PM

Hokay, it's sorting. Is it possible to sort on two or more elements?

John

samjudson · March 12th, 2008, 02:07 AM

Code:

List<csvLine> lines = new List<csvLine>();

The you can just do:

Code:

foreach(csvLine line in lines)
{
   Console.WriteLine(line.clNumb);
}

The Compare function returns 0 if the two items are the same, so simply check that value and if they are then move to the second item you want ot sort by:

Code:

public int Compare(object x, object y)
{
  csvLine l1 = x as csvLine;
  csvLine l2 = y as csvLine;
  if (l1 != null && l2 != null)
  {
    int c = Comparer.Default.Compare(l1.clNumb, l2.clNumb);
    if( c != 0 )
      return c;
    return Comparer.Default.Compare(l1.clChan, l2.clChan);
  }
  else
  {
    throw new ArgumentException("One or both objects to compare are not csvLine objects.");
  }
}

/- Sam Judson : Wrox Technical Editor -/

Devlin · March 12th, 2008, 10:47 AM

Thank you. That helps immensely.

John