Query for Sentences that Contain a Specified Set of Words

// ----------------------------------------------------------------------------
// Query for Sentences that Contain a Specified Set of Words
// https://msdn.microsoft.com/en-us/library/mt693048.aspx
//
// This example shows how to find sentences in a text file that contain matches
// for each of a specified set of words. Although the array of search terms is
// hard-coded in this example, it could also be populated dynamically at
// runtime. In this example, the query returns the sentences that contain the
// words "Historically," "data," and "integrated."
//
// ----------------------------------------------------------------------------

using System.Linq;
using System;

class FindSentences
{
    static void Main()
    {
        string text =
        @"Historically, the world of data and the world of objects " +
        @"have not been well integrated. Programmers work in C# or Visual Basic " +
        @"and also in SQL or XQuery. On the one side are concepts such as classes, " +
        @"objects, fields, inheritance, and .NET Framework APIs. On the other side " +
        @"are tables, columns, rows, nodes, and separate languages for dealing with " +
        @"them. Data types often require translation between the two worlds; there are " +
        @"different standard functions. Because the object world has no notion of query, a " +
        @"query can only be represented as a string without compile-time type checking or " +
        @"IntelliSense support in the IDE. Transferring data from SQL tables or XML trees to " +
        @"objects in memory is often tedious and error-prone.";

        // Split the text block into an array of sentences.
        string[] sentences = text.Split(new char[] { '.', '?', '!' });

        // Define the search terms. This list could also be dynamically populated at runtime.
        string[] wordsToMatch = { "Historically", "data", "integrated" };

        // Find sentences that contain all the terms in the wordsToMatch array.
        // Note that the number of terms to match is not specified at compile time.
        var sentenceQuery = from sentence in sentences
                            let w = sentence.Split(new char[] { '.', '?', '!', ' ', ';', ':', ',' },
                                                    StringSplitOptions.RemoveEmptyEntries)
                            where w.Distinct().Intersect(wordsToMatch).Count() == wordsToMatch.Count()
                            select sentence;

        // Execute the query. Note that you can explicitly type
        // the iteration variable here even though sentenceQuery
        // was implicitly typed.
        foreach (string str in sentenceQuery)
        {
            Console.WriteLine(str);
        }

        // Keep the console window open in debug mode.
        Console.WriteLine("Press any key to exit");
        Console.ReadKey();
    }
}

/*
    Output:
    Historically, the world of data and the world of objects have not been well integrated
*/