How to use Generics in C#

Suppose we have a simple class People

Code:

protected class People : IComparable
    {
        protected string name = String.Empty;
        protected int age = 0;
        protected double salary = 0.0d;
        
        /// <summary>
        /// The constructor of the class People
        /// </summary>
        /// <param name="n"></param>
        /// <param name="a"></param>
        /// <param name="s"></param>
        public People(string n, int a, double s)
        {
            name = n;
            age = a;
            salary = s;
        }

        /// <summary>
        /// Override the ToString() method
        /// </summary>
        /// <returns></returns>
        override public string ToString()
        {
            return String.Format("{0:s}, {1:G} - Salary: {2:c}",name, age, salary);
        }

        /// <summary>
        /// Override the CompareTo method,
        /// compare name fields
        /// </summary>
        /// <param name="obj"></param>
        /// <returns></returns>
        public int CompareTo(object obj)
        {
            People otherPeople = obj as People;
            if (otherPeople != null)
                return this.name.CompareTo(otherPeople.name);
            else
                throw new ArgumentException("Object is not a People");
        }
    }

We want to insert objects of type People in a list, and then manipulating them.

Code:

List<People> people = new List<People>();
people.Add(new People("Yasmine", 32, 1800.00d));
people.Add(new People("Gabrielle", 38, 2300.00d));
people.Add(new People("Lynette", 35, 2200.00d));
people.Add(new People("Asia", 33, 1900.00d));
people.Add(new People("Daisy", 36, 2000.00d));
people.Add(new People("Lorelayne", 39, 2100.00d));
people.Add(new People("Jenny", 36, 2300.00d));
people.Add(new People("Lisa", 34, 2600.00d));
people.Add(new People("Ylenia", 37, 1700.00d));

Response.Write("<h2>List of people (not sorted)</h2>");
foreach(People p in people)
{
	Response.Write(p.ToString() + "<br />");
}

// Sort the List, the CompareTo method, of the class People, determines which field will be performed comparing
people.Sort();

Response.Write("<h2>List of people (sorted by name ASC)</h2>");
foreach (People p in people)
{
	Response.Write(p.ToString() + "<br />");
}

// Reverses the order of the elements of the list
people.Reverse();

Response.Write("<h2>List of people (sorted by name DESC)</h2>");
foreach (People p in people)
{
	Response.Write(p.ToString() + "<br />");
}

Response.Write("<h3>Some information of the list</h3>");
Response.Write("<code>people.Capacity</code>: " + people.Capacity + "<br />");
Response.Write("<code>people.Count</code>: " + people.Count + "<br />");

Here is the result for the sample:

List of people (not sorted)

Yasmine, 32 - Salary: $1,800.00
Gabrielle, 38 - Salary: $2,300.00
Lynette, 35 - Salary: $2,200.00
Asia, 33 - Salary: $1,900.00
Daisy, 36 - Salary: $2,000.00
Lorelayne, 39 - Salary: $2,100.00
Jenny, 36 - Salary: $2,300.00
Lisa, 34 - Salary: $2,600.00
Ylenia, 37 - Salary: $1,700.00

List of people (sorted by name ASC)

Asia, 33 - Salary: $1,900.00
Daisy, 36 - Salary: $2,000.00
Gabrielle, 38 - Salary: $2,300.00
Jenny, 36 - Salary: $2,300.00
Lisa, 34 - Salary: $2,600.00
Lorelayne, 39 - Salary: $2,100.00
Lynette, 35 - Salary: $2,200.00
Yasmine, 32 - Salary: $1,800.00
Ylenia, 37 - Salary: $1,700.00

List of people (sorted by name DESC)

Ylenia, 37 - Salary: $1,700.00
Yasmine, 32 - Salary: $1,800.00
Lynette, 35 - Salary: $2,200.00
Lorelayne, 39 - Salary: $2,100.00
Lisa, 34 - Salary: $2,600.00
Jenny, 36 - Salary: $2,300.00
Gabrielle, 38 - Salary: $2,300.00
Daisy, 36 - Salary: $2,000.00
Asia, 33 - Salary: $1,900.00

Some information of the list

people.Capacity: 16
people.Count: 9