Question

I am programming a program to search the name from the list and I need to find them even if the keyword is not in front of the names (that’s what I mean non-prefix)

e.g. if I my list is the music instruments and I type “guit” to the search textbox.
It should find the names “Guitar, Guitarrón, Acoustic Guitar, Bass Guitar, …”
or something like this Longdo Dictionary’s search suggestion.

here is my simple and stupid algorithm (that’s all I can do)

    const int SEARCHROWLIMIT = 30;
    private string[] DoSearch(string Input, string[] ListToSearch)
    {
        List<string> FoundNames = new List<string>();

        int max = 0;
        bool over = false;
        for (int k = 0; !over; k++)
        {
            foreach (string item in ListToSearch)
            {
                max = (max > item.Length) ? max : item.Length;
                if (k > item.Length) continue;
                if (k >= max) { over = true; break; }
                if (!Input.Equals("Search")
                    && item.Substring(k, item.Length - k).StartsWith(Input, StringComparison.OrdinalIgnoreCase))
                {
                    bool exist = false;
                    int i = 0;
                    while (!exist && i < FoundNames.Count)
                    {
                        if (item.Equals(FoundNames[i]))
                        {
                            exist = true;
                            break;
                        }
                        i++;
                    }
                    if (!exist && FoundNames.Count < SEARCHROWLIMIT)
                        FoundNames.Add(item);
                    else if (FoundNames.Count >= SEARCHROWLIMIT) over = true;
                }
            }
        }
        return FoundNames.ToArray();
    }

I think this algorithm is too slow for a large number of names and after several trial-and-error, I decided to add SEARCHROWLIMIT to breaks the operation
And I also think there’re some readymade methods that can do that.

And another problem is I need to search music instruments by a category like strings, percussions, … and by the country of origins. So I need to search them with filter by type and country.

How can I achieve this?

Answer 1

Using LINQ you could write code like this:

var resultSet = products

    // filter products by category
    .Where(product => product.Category == "strings")

    // filter products by origin
    .Where(product => product.Origin == "italy")

    // filter products whose name contains a word starting with "guit"
    .Where(product => (" " + product.Name).Contains(" guit"))

    // limit the result set to the first 30 matching products
    .Take(30);

If your sets of products is reasonably small, you can use LINQ-to-Objects. Otherwise you should use a database and have a look at LINQ-to-SQL.