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Search for Sentences in a Text File in C#

In this exercise, you will create a program that reads the content of a text file and saves it into an ArrayList. The program will then ask the user to enter a word or sentence and search for it within the lines of the file. If the word or sentence is found, the program will display all the lines that contain it. The user can continue entering different words or sentences to search until they choose to stop by entering an empty string.

This exercise helps you practice file reading, string searching, and using collections like ArrayList to manage dynamic data. The program should be able to handle cases where no matches are found, and the search should be case-sensitive.



Group

Dynamic Memory Management in C#

Objective

1. Read the content of a text file and save it to an ArrayList.
2. Prompt the user to enter a word or sentence.
3. Search the ArrayList for any lines containing the entered word or sentence.
4. Display all matching lines to the user.
5. Repeat the process until the user enters an empty string to stop.

Create a program that reads a text file, saves its content to an ArrayList, and asks the user to enter sentences to search within the file.

Example C# Exercise

 Copy C# Code 
using System;
using System.Collections;
using System.IO;

class Program
{
    static void Main()
    {
        // Create an ArrayList to store the lines from the text file
        ArrayList lines = new ArrayList();

        // Read the content of a text file and store it in the ArrayList
        try
        {
            string[] fileLines = File.ReadAllLines("textfile.txt"); // Read the file
            foreach (string line in fileLines)
            {
                lines.Add(line);  // Add each line from the file into the ArrayList
            }
        }
        catch (FileNotFoundException)
        {
            Console.WriteLine("The file could not be found.");
            return;
        }

        // Main loop where the user enters search terms
        while (true)
        {
            Console.WriteLine("\nEnter a word or sentence to search (or press ENTER to exit): ");
            string searchTerm = Console.ReadLine();  // Get user input

            // Exit the loop if the user enters an empty string
            if (string.IsNullOrWhiteSpace(searchTerm))
            {
                break;  // Exit the program
            }

            // Flag to check if any matches are found
            bool found = false;

            // Search through the ArrayList and display matching lines
            foreach (string line in lines)
            {
                if (line.Contains(searchTerm))  // Check if the line contains the search term
                {
                    Console.WriteLine(line);  // Display the matching line
                    found = true;
                }
            }

            // If no matches were found, inform the user
            if (!found)
            {
                Console.WriteLine("No matching lines found.");
            }
        }

        // Message when exiting the program
        Console.WriteLine("Exiting program...");
    }
}

 Output

Enter a word or sentence to search (or press ENTER to exit): Dog
The quick brown dog jumped over the lazy dog.
A dog barked loudly.

Enter a word or sentence to search (or press ENTER to exit): cat
No matching lines found.

Enter a word or sentence to search (or press ENTER to exit): 
Exiting program...

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