02.8.08.SentenceExtractRegex

using System;
using System.Text;
using System.Text.RegularExpressions;

class SentencesExtractRegex
{
    static void SubstringCounter(string textTemp, string targetTemp)
    {
        string text = textTemp; // toUpper
        string target = targetTemp; // toUpper
        StringBuilder sb = new StringBuilder();
        string[] parts = Regex.Split(text, @"\.\n|\. ");
        sb.AppendFormat(@"\b{0}\b", target);
        string pattern = sb.ToString();
        foreach (var sentence in parts)
        {
            Match match = Regex.Match(sentence, pattern);
            bool sign = false;
            while (match.Success)
            {
                sign = true;
                match = match.NextMatch();
            }
            if (sign == true)
            {
                Console.WriteLine(sentence);
            }
        }

        return;
    }

    static void Main()
    {
        string someText = "We are living in an yellow submarine. We don't have anything else. Inside the submarine is very tight. So we are drinking all the day. We will move out of it in 5 days.";
        string target = "in";
        SubstringCounter(someText, target);
    }
}