SomeSt

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication4
{
    class Program
    {
        public static bool Found(char[] sentence, char[] word)
        {
            int k = 0;
            for (int i = 0; i < sentence.Length; i++)
            {
                if (sentence[i] == word[k])
                    k++;
                else
                    k = 0;
                if (k == word.Length)
                {
                    if (i == sentence.Length - 1 || i - word.Length + 1 == 0 || sentence[i + 1] == ' ' && sentence[i - word.Length] == ' ')
                        return true;
                    k = 0;
                    Console.WriteLine(sentence[i]);
                }
            }
            return false;
        }
        public static int Count(char[] sentence, char[] word)
        {
            int count = 0, k = 0;
            for (int i = 0; i < sentence.Length; i++)
            {
                if (sentence[i] == word[k])
                    k++;
                else
                    k = 0;
                if (k == word.Length)
                {
                    if (i == sentence.Length - 1 || i - word.Length + 1 == 0 || sentence[i + 1] == ' ' && sentence[i - word.Length] == ' ')
                        count++;
                    k = 0;
                }
            }
            return count;
        }
        public static void Replace(char[] sentence, char[] word, char[] newWord)
        {
            int k = 0;
            for (int i = 0; i < sentence.Length; i++)
            {
                if (sentence[i] == word[k])
                    k++;
                else
                    k = 0;
                if (k == word.Length)
                {
                    for (int j = i - k + 1; j < i + 1; j++)
                        sentence[j] = newWord[j + k - i - 1];
                    k = 0;
                }
            }
        }
        public static void RealReplace(char[] sentence, char[] word, char[] newWord)
        {
            int k = 0;
            int lastChar = 0;
            while (sentence[lastChar] != ' ')
                lastChar++;
            for (int i = 0; i < lastChar; i++)
            {
                if (sentence[i] == word[k])
                    k++;
                else
                    k = 0;
                if (k == word.Length)
                {
                    for (int m = lastChar + newWord.Length - word.Length - 1; m > i; m--)
                        sentence[m] = newWord[lastChar + newWord.Length - word.Length - 1 - m];
                    for (int j = i - word.Length + 1; j < i - word.Length + newWord.Length; j++)
                        sentence[j] = newWord[j - i + word.Length - 1];
                    k = 0;
                }
            }
        }
        static void Main(string[] args)
        {
            char[] arr1 = new char[] { 'a', 'b', 'c', 'x', 'y', 'z', 'f', 'k', 'l', 'm', 'a', 'b', 'c', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ' };
            char[] arr2 = new char[] { 'a', 'b', 'c', 'd' };
            char[] arr3 = new char[] { '1', '2', '3', '4' };
            Console.WriteLine("Is word found? " + Found(arr1, arr2));
            Console.WriteLine("Word appears " + Count(arr1, arr2) + " times");
            Console.WriteLine("Word will now be replaced");
            Replace(arr1, arr2, arr3);
            Console.WriteLine("Updated sentence: ");
            foreach (char c in arr1)
                Console.Write(c);
            Console.WriteLine();
        }
    }
}