Question

I have a dictionary with the following data:

Key    Value
1      Introduction
1.1    General
1.1.1  Scope
1.2    Expectations
2      Background
2.1    Early Development
...

What I’d like to do is figure out a way – in C# – to create a new list (or append to an array) with the values concatenated based on the list-style key, like so:

Key    Value              Concatenation
1      Introduction       Introduction
1.1    General            Introduction - General
1.1.1  Scope              Indroduction - General - Scope
1.2    Expectations       Introduction - Expectations
2      Background         Background
2.1    Early Development  Background - Early Development
...

There is no set number of sublevels for the key but it will always be in numeric format. Any thoughts?

Answer 1

This obviously needs to be cleaned up and made more efficient, but you can do this pretty simply using a recursive method:

static string GetConcatenationRecursively(Dictionary<string, string> d, string key)
{
    if (key.Length == 1)
    {
        return d[key];
    }
    else
    {
        return string.Format(
            "{0} - {1}",
            GetConcatenationRecursively(d, key.Substring(0, key.LastIndexOf('.'))),
            d[key]);
    }
}

This would be called like this:

Dictionary<string, string> d = new Dictionary<string, string>();
d.Add("1", "Introduction");
d.Add("1.1", "General");
d.Add("1.1.1", "Scope");
d.Add("1.2", "Expectations");
d.Add("2", "Background");
d.Add("2.1", "Early Development");

List<Tuple<string, string, string>> list = new List<Tuple<string, string, string>>();
foreach (string key in d.Keys)
{
    list.Add(new Tuple<string, string, string>(key, d[key], GetConcatenationRecursively(d, key)));
}

Needs lots of error handling as well; this obviously assumes a well-formed input. But you should be able to take it from here.