Question

This is all in C#, using .NET 3.5.

I have a list populated with book information. Each item contains the course abbreviation, the course number, and the section of the course:

myList1.Add("ACCT", 100, "1");
myList1.Add("ACCT", 100, "2");
myList1.Add("BUS", 101, "1"); and so on...

What I need to do is combine items that have the same curriculum and course so the sections are in one string.

"ACCT", 100, "1, 2"
"BUS", 101, "1"

How should I go about comparing each item in the list to check for matches? The original method utilized a long chain of if-else statements and used 5 lists. I’m trying to avoid that. Is this question on the right track for me?

EDIT: To answer Philipp’s question, the list uses a class containing those properties like Thomas Levesque’s answer:

class Course
{
    public string Abbreviation { get; set; }
    public int Number { get; set; }
    public string Section { get; set; }
}

And is populated by a method from a DataAccess class:

List<Course> list = DataAccess.GetData();

Hope that clears that up.

Answer 1

Assuming the following class declaration:

class Course
{
    public string Abbreviation { get; set; }
    public int Number { get; set; }
    public string Section { get; set; }
}

You can do something like that:

var list = new List<Course>
{
    new Course { Abbreviation = "ACCT", Number = 100, Section = "1" },
    new Course { Abbreviation = "ACCT", Number = 100, Section = "2" },
    new Course { Abbreviation = "BUS", Number = 101, Section = "1" },
    ...
};

var query = from c in list
            group c by new { c.Abbreviation, c.Number } into g
            select string.Format("\"{0}\", {1}, \"{2}\"",
                                 g.Key.Abbreviation,
                                 g.Key.Number,
                                 String.Join(", ", g.Select(c => c.Section).ToArray()));

List<string> result = query.ToList();