c# List<T> Sort : by Chinese strokes

Question

I have a webpage, in which there is a sort that I have to order the list by Chinese strokes.

I have created an application containing code like this:

List<Student> stuList = new List<Student>() { 
          new Student("上海"),
           new Student("深圳"),
            new Student("广州"),
             new Student("香港")
            };
        System.Globalization.CultureInfo strokCi = new System.Globalization.CultureInfo("zh-tw");
        System.Threading.Thread.CurrentThread.CurrentCulture = strokCi; ;
        //stuList.sort();

but there is an error: At least one object must implement IComparable.

What does this mean and how can I fix it?

Answer 1

You need to have your Student class implement the IComparable interface. This requires implementing a method CompareTo, which can simply return the result of calling CompareTo between the strings you're trying to order by.

For example, if the constructor initializes a name field, you might have something like this:

public class Student : IComparable
{
    private string name;

    public Student(string name)
    {
        this.name = name;
    }

    public int CompareTo(object other)
    {
        Student s = other as Student;
        if (s == null)
        {
            throw new ArgumentException("Students can only compare with other Students");
        }

        return this.name.CompareTo(s.name);
    }
}

Answer 2

Student must implement IComparable.

Answer 3

Rather than implement IComparable, why not just use a bit of LINQ?

stuList.OrderBy( s => s.Name ) //.ToList if you really want a List

Answer 4

public class Student : IComparable
{
    private string message = null;
    public Student(string message)
    {
        this.message = message;
    }
    #region IComparable Members

    public int CompareTo(object obj)
    {
        // implement your logic, here is a example:
        if (obj != null)
            return message.CompareTo(((Student)obj).message);
        return int.MinValue;
    }

    #endregion
}