Question

I have got the problem with creating an array list in c#, Can you please help me.
I need to create the array list to remove all the pipes that have lengths lower than 19.

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            ArrayList lstPipeTypes = new ArrayList();

            lstPipeTypes.Add(new PipesList("PVC Pipes"));
            ((PipesList)lstPipeTypes[0]).Pipes.Add(new Pipe("The blue pipe", 12));
            ((PipesList)lstPipeTypes[0]).Pipes.Add(new Pipe("The red pipe", 15));
            ((PipesList)lstPipeTypes[0]).Pipes.Add(new Pipe("The silver pipe", 6));
            ((PipesList)lstPipeTypes[0]).Pipes.Add(new Pipe("The green pipe", 52));

            lstPipeTypes.Add(new PipesList("Iron Pipes"));
            ((PipesList)lstPipeTypes[1]).Pipes.Add(new Pipe("The gold pipe", 9));
            ((PipesList)lstPipeTypes[1]).Pipes.Add(new Pipe("The orange pipe", 115));
            ((PipesList)lstPipeTypes[1]).Pipes.Add(new Pipe("The pink pipe", 1));

            lstPipeTypes.Add(new PipesList("Chrome Pipes"));
            ((PipesList)lstPipeTypes[2]).Pipes.Add(new Pipe("The grey pipe", 12));
            ((PipesList)lstPipeTypes[2]).Pipes.Add(new Pipe("The black pipe", 15));
            ((PipesList)lstPipeTypes[2]).Pipes.Add(new Pipe("The white pipe", 19));
            ((PipesList)lstPipeTypes[2]).Pipes.Add(new Pipe("The brown pipe", 60));
            ((PipesList)lstPipeTypes[2]).Pipes.Add(new Pipe("The peach pipe", 16));


            RemoveTheSmallPipes(lstPipeTypes);
        }


        public static ArrayList RemoveTheSmallPipes(ArrayList lstPipeTypes)
        {

            //should remove all pipes that have lengths lower than 19.

            return lstPipeTypes;

        }
    }

    class PipesList
    {
        public string pipeType;
        public ArrayList Pipes;

        public PipesList(string newBoxType)
        {
            pipeType = newBoxType;
            Pipes = new ArrayList();
        }
    }

    class Pipe
    {
        public string name;
        public float length;

        public Pipe(string newName, float newLength)
        {
            this.name = newName;
            this.length = newLength;
        }
    }


}

I have created the two classes called Pipe and PipeList as well and I need to place the array list in the “RemoveTheSmallPipes” method. But I am confused now to write the rest. Please help me to remove all the pipes that have lengths lower than 19.

Answer 1

Here’s your method without changing anything else:

public static ArrayList RemoveTheSmallPipes(ArrayList lstPipeTypes)
{

    for (int i = 0; i < lstPipeTypes.Count; i++)
    {
        ArrayList pipesToRemove = new ArrayList();
        int pipeCount = ((PipesList)lstPipeTypes[i]).Pipes.Count;
        for (int j = 0; j < pipeCount; j++)
        {
            if (((Pipe)((PipesList)lstPipeTypes[i]).Pipes[j]).length < 19)
            {
                pipesToRemove.Add(j);
            }
        }

        for (int k = 0; k < pipesToRemove.Count; k++)
        {
            ((PipesList)lstPipeTypes[i]).Pipes.RemoveAt((int)pipesToRemove[k]);
        }
    }

    return lstPipeTypes;
}

It’s really a shame You cannot change anything else because this code is not up to standards anymore. To show You a difference here’s modified C# 4.0 version:

Console:

static void Main(string[] args)
{
    var pipeTypes = new List<PipePile>();

    pipeTypes.Add(new PipePile("PVC Pipes", new List<Pipe>
        {
            new Pipe { Name = "The blue pipe", Length = 12 },
            new Pipe { Name = "The red pipe", Length = 15 },
            new Pipe { Name = "The silver pipe", Length = 6 },
            new Pipe { Name = "The green pipe", Length = 52 }
        }));

    pipeTypes.Add(new PipePile("Iron Pipes", new List<Pipe>
        {
            new Pipe { Name = "The gold pipe", Length = 9 },
            new Pipe { Name = "The orange pipe", Length = 115 },
            new Pipe { Name = "The pink pipe", Length = 1 }
        }));

    pipeTypes.Add(new PipePile("Chrome Pipes", new List<Pipe>
        {
            new Pipe { Name = "The grey pipe", Length = 12 },
            new Pipe { Name = "The black pipe", Length = 15 },
            new Pipe { Name = "The white pipe", Length = 19 },
            new Pipe { Name = "The brown pipe", Length = 60 },
            new Pipe { Name = "The peach pipe", Length = 16 }
        }));

    // Remove all pipes with length longer than 19
    pipeTypes.ForEach(pile => pile.Pipes.RemoveAll(pipe => pipe.Length > 19));
}

Classes:

public class Pipe
{
    public string Name { get; set; }
    public float Length { get; set; }
}

public class PipePile
{
    public string PipeType { get; set; }
    public List<Pipe> Pipes { get; set; }

    public PipePile(string pipeType, List<Pipe> pipes)
    {
        PipeType = pipeType;
        Pipes = pipes;
    }

    public PipePile(): this("", new List<Pipe>())
    {
    }
}

As You can see it’s quite different, but much more elegant (Linq FTW! 🙂 )