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problem with sorting car names RSS

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Last post Jul 30, 2012 06:40 AM by amigo 1

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amigo 1

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199 Posts

problem with sorting car names

Jul 18, 2012 05:33 AM|LINK

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace Scratch_Pad2

{

    class host

    {

        static void Main(string[] args)

        {



// create an array of car objects

       car[] arrayOfCars = new car[6]

                                            { new car("Merc",1992),

                                               new car("Toyota",1988),

                                               new car("Buick",1932),

                                               new car("Bugatti",1932),

                                               new car("Rolls Royce",1999),

                                               new car("Honda",1977)

                                             };



//unsorted output

// ----------------------------------

Console.WriteLine("unsorted output");

            foreach( car c in arrayOfCars)

Console.WriteLine (c.make +"\t\t"+ c.year);

// default sort

            Array.Sort(arrayOfCars);

            Console.WriteLine("default sorted output");

            foreach(car c in arrayOfCars)

            Console.WriteLine(c.make + "\t\t" + c.year);

// Ascending sort with IComparer

            Array.Sort(arrayOfCars, car. sortYearAscending());

            Console.WriteLine("Ascending sort with IComparer");

            foreach (car c in arrayOfCars)

            Console.WriteLine(c.make + "\t\t" + c.year);

            Console.Read();



        }

    }

   public class car : IComparable

   {



        public int year;

       public string make;

        public car(string Make , int Year)

        {

            make = Make;

            year = Year;

        }

        int IComparable.CompareTo(object obj)

        {

            car c = (car)obj;

            return

                string.Compare(this.make , c.make);}

private class sortYearAscendingHelper:IComparer{

    int IComparer.Compare(object a, object b)

    {

        car c1 = (car)a;

        car c2=(car)b;

        if (c1.year >c2.year) return 1 ;

        if (c1.year <c2.year) return -1 ;

        else return 0 ;

    }

    public static IComparer sortYearAscending()

    {

        return (IComparer) new sortYearAscendingHelper();

    }



        }

   }

}

Please note that the output comes upto the default sort (including unsorted)

Even the Console.Writeline part of the Ascending Sort does not output why?

Error      1              Using the generic type 'System.Collections.Generic.IComparer<T>' requires 1 type arguments                C:\Users\lenovo\documents\visual studio 2010\Projects\Scratch Pad2\host.cs 92           39           Scratch Pad2

Error      2              Using the generic type 'System.Collections.Generic.IComparer<T>' requires 1 type arguments                C:\Users\lenovo\documents\visual studio 2010\Projects\Scratch Pad2\host.cs 103         19           Scratch Pad2

Can you please help me with this code

Re: problem with sorting car names

Jul 18, 2012 07:51 AM|LINK

Here you are calling "sortYearAscending" from the client, but that static method comes under sortYearAscending class, it should move to car class, I tested below code and working good.

public class car : IComparable
    {
        public int year;
        public string make;
        public car(string Make, int Year)
        {
            make = Make;
            year = Year;
        }
        int IComparable.CompareTo(object obj)
        {
            car c = (car)obj;
            return string.Compare(this.make, c.make);
        }

        private class sortYearAscendingHelper : IComparer
        {
            int IComparer.Compare(object a, object b)
            {
                car c1 = (car)a;
                car c2 = (car)b;
                if (c1.year > c2.year) return 1;
                if (c1.year < c2.year) return -1;
                else return 0;
            }

        }

        public static IComparer sortYearAscending()
        {
            return (IComparer)new sortYearAscendingHelper();
        }

    }

Mãsthän Oli
playingOOPS | மெய்ப்பொருள் காண்பதறிவு
Mark as Answer If you find helpful

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Paul Linton

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2535 Posts

Re: problem with sorting car names

Jul 18, 2012 10:32 PM|LINK

Sorry, I didn't read all your code (could you remove some of the blank lines so that there is not so much scrolling up and down to do). Do you realise that sorting is very, very easy if you use Linq?

var sortedCars = arrayOfCars.OrderBy(c => c.Make);

var recentCarsFirst = arrayOfCars.OrderByDescending(c => c.Year);

You don't need any of that IComparaable stuff

Got a c# problem? Try .NET Book Zero from Charles Petzold, it's a free pdf.
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Miikey

Member

21 Points

41 Posts

Re: problem with sorting car names

Jul 19, 2012 12:44 AM|LINK

Are you trying to sort them in Alphabetical order? If so its much easier.

within the column headter text include: SortExpression="columnname" at the end.

Also if your using a gv include AllowSorting="true"

Please mark my answer if it helped you,
I would greatly appreciate it.
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amigo 1

Member

60 Points

199 Posts

Re: problem with sorting car names

Jul 19, 2012 06:14 AM|LINK

s demanded by teacher Paul Linton, below I give you the same question without the "un-necessary gaps":

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

namespace Scratch_Pad2 {class host {static void Main(string[] args)

        { // create an array of car objects

       car[] arrayOfCars = new car[6]

       { new car("Merc",1992), new car("Toyota",1988), new car("Buick",1932),

       new car("Bugatti",1932), new car("Rolls Royce",1999), new car("Honda",1977)};

//unsorted output

Console.WriteLine("unsorted output");

            foreach( car c in arrayOfCars)

Console.WriteLine (c.make +"\t\t"+ c.year);

// default sort

Array.Sort(arrayOfCars);

            Console.WriteLine("default sorted output");

            foreach(car c in arrayOfCars) Console.WriteLine(c.make + "\t\t" + c.year);

// Ascending sort with IComparer

Array.Sort(arrayOfCars, car. sortYearAscending());

            Console.WriteLine("Ascending sort with IComparer");

            foreach (car c in arrayOfCars)

            Console.WriteLine(c.make + "\t\t" + c.year);

            Console.Read();}}

          public class car : IComparable

   { public int year;

       public string make;

public car(string Make , int Year)

        {make = Make;

            year = Year;}

int IComparable.CompareTo(object obj)

        {car c = (car)obj;

            return string.Compare(this.make , c.make);}

private class sortYearAscendingHelper:IComparer{

    int IComparer.Compare(object a, object b)

    {car c1 = (car)a;     car c2=(car)b;

        if (c1.year >c2.year) return 1 ;   if (c1.year <c2.year) return -1 ;

        else return 0 ;} public static IComparer sortYearAscending()

    { return (IComparer) new sortYearAscendingHelper(); }}}}

       Please note that the output comes upto the default sort (including unsorted)

Even the Console.Writeline part of the Ascending Sort does not output why?

Error      1              Using the generic type 'System.Collections.Generic.IComparer<T>' requires 1 type arguments                C:\Users\lenovo\documents\visual studio 2010\Projects\Scratch Pad2\host.cs 92           39           Scratch Pad2

Error      2              Using the generic type 'System.Collections.Generic.IComparer<T>' requires 1 type arguments                C:\Users\lenovo\documents\visual studio 2010\Projects\Scratch Pad2\host.cs 103         19           Scratch Pad2

I do not know LINQ
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Paul Linton

Star

13411 Points

2535 Posts

Re: problem with sorting car names

Jul 19, 2012 06:17 AM|LINK

amigo 1
I do not know LINQ
Would turning so many lines of code which don't work in to a single line of working code which does the equivalent operation be sufficient incentive to learn?

Got a c# problem? Try .NET Book Zero from Charles Petzold, it's a free pdf.
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amigo 1

Member

60 Points

199 Posts

Re: problem with sorting car names

Jul 19, 2012 06:41 AM|LINK

Paul Linton
Would turning so many lines of code which don't work in to a single line of working code which does the equivalent operation be sufficient incentive to learn?

Now I will

thanks
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amigo 1

Member

60 Points

199 Posts

Re: problem with sorting car names

Jul 20, 2012 06:42 AM|LINK

Mastan Oli
Here you are calling "sortYearAscending" from the client, but that static method comes under sortYearAscending class, it should move to car class, I tested below code and working good

but you see I am still getting the same set of errors

Re: problem with sorting car names

Jul 24, 2012 08:40 AM|LINK

Hi,

Check your souce code again and again and at last I decide to copy your source code to test. Then I get what cause lead to this error "Using the generic type 'System.Collections.Generic.IComparer<T>' requires 1 type arguments ". This error indicates you were using a generic Icomparer and you need to provide a type arguments for it. To avoid providing one type arguments, you need to use the full reference like below:

private class sortYearAscendingHelper:System.Collections.IComparer

Now I change your souce code and test it, works fine:

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            // create an array of Car  objects

            Car[] arrayOfCars = new Car[6]{ new Car("Merc",1992),
                new Car("Toyota",1988),
                new Car("Buick",1932),
                new Car("Bugatti",1932),
                new Car("Rolls Royce",1999),
                new Car("Honda",1977)};
            Console.WriteLine("unsorted output");

            foreach (Car c in arrayOfCars)
            {
                Console.WriteLine(c.Make + "\t\t" + c.Year);
            }
            // default sort

            Array.Sort(arrayOfCars);
            Console.WriteLine("default sorted output");
            foreach (Car c in arrayOfCars)
            {
                Console.WriteLine(c.Make + "\t\t" + c.Year);
            }

            // Ascending sort with IComparer



            Array.Sort(arrayOfCars, Car.sortYearAscending());
            Console.WriteLine("Ascending sort with IComparer");

            foreach (Car c in arrayOfCars)
            {
                Console.WriteLine(c.Make + "\t\t" + c.Year);
            }
            Console.Read();

        }
    }
    class Car : IComparable
    {
        string make;
        int year;

        public Car(string make, int year)
        {
            this.make = make;
            this.year = year;
        }
        public string Make
        {
            get { return make; }
            set { this.make = value; }
        }
        public int Year
        {
            get { return year; }
            set { this.year = value; }
        }

        public int CompareTo(object obj)
        {
            if (obj == null)
            {
                return 0;
            }
            Car Car = obj as Car;
            return this.year.CompareTo(Car.Year);
        }
        private class sortYearAscendingHelper : System.Collections.IComparer
        {

            int System.Collections.IComparer.Compare(object a, object b)
            {
                Car c1 = (Car)a; Car c2 = (Car)b;

                if (c1.year > c2.year) return 1; if (c1.year < c2.year) return -1;

                else return 0;
            }

        }
        public static System.Collections.IComparer sortYearAscending()
        {
            return (System.Collections.IComparer)new sortYearAscendingHelper();

        }
    }
}

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Marked as answer by mamba dai - msft on Jul 29, 2012 03:09 AM

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amigo 1

Member

60 Points

199 Posts

Re: problem with sorting car names

Jul 27, 2012 02:17 PM|LINK

Hello Mamba Dai

the help that I got from you sadly gets un-returned, but to make an attempt to rectify this , please let me know how to mark this as an answer given , i have already done that , as this is the way that a good answer must be responded

regards

amigo1

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