How to resolve the algorithm Append a record to the end of a text file step by step in the C# programming language

Published on 12 May 2024 09:40 PM
#C_Sharp

How to resolve the algorithm Append a record to the end of a text file step by step in the C# programming language

Table of Contents

Problem Statement

Many systems offer the ability to open a file for writing, such that any data written will be appended to the end of the file. Further, the file operations will always adjust the position pointer to guarantee the end of the file, even in a multitasking environment. This feature is most useful in the case of log files, where many jobs may be appending to the log file at the same time, or where care must be taken to avoid concurrently overwriting the same record from another job.

Given a two record sample for a mythical "passwd" file: Resulting file format: should mimic Linux's /etc/passwd file format with particular attention to the "," separator used in the GECOS field. But if the specific language has a particular or unique format of storing records in text file, then this format should be named and demonstrated with an additional example. Expected output: Finally: Provide a summary of the language's "append record" capabilities in a table. eg. Alternatively: If the language's appends can not guarantee its writes will always append, then note this restriction in the table. If possible, provide an actual code example (possibly using file/record locking) to guarantee correct concurrent appends.

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Append a record to the end of a text file step by step in the C# programming language

This C# code manipulates and appends a new record to a text file in the typical system password file format. Here's a detailed breakdown:

  1. Classes and Structures:

    • PasswordRecord: This class represents a single record in the password file. It contains various fields like account name, password, user ID (UID), group ID (GID), etc.
    • Each field has a constructor to initialize the record with appropriate values.

  2. Main Function:

    • Main method is the entry point of the program.
    • It creates three instances (records) of PasswordRecord: jsmith, jdoe, and xyz, with different values for each field.

  3. Writing Records to File:

    • File.WriteAllLines("passwd.txt", new string[] { jsmith.ToString(), jdoe.ToString() }): This line writes the jsmith and jdoe records to a file named "passwd.txt" in the system's password file format.
    • jsmith.ToString() and jdoe.ToString() convert these records into strings in the required format.

  4. Appending a New Record:

    • File.AppendAllText("passwd.txt", xyz.ToString()): This appends the xyz record to the same "passwd.txt" file.

  5. Verifying Appended Record:

    • string[] lines = File.ReadAllLines("passwd.txt"): This reads all the lines (records) in the "passwd.txt" file and stores them in the lines array.
    • Console.WriteLine("Appended record: " + lines[2]): This prints the third line (index 2) of the lines array, which should be the appended xyz record.

Source code in the csharp programming language

using System;
using System.IO;

namespace AppendPwdRosetta
{
    class PasswordRecord
    {
        public string account, password, fullname, office, extension, homephone, email, directory, shell;
        public int UID, GID;
        public PasswordRecord(string account, string password, int UID, int GID, string fullname, string office, string extension, string homephone, 
            string email, string directory, string shell)
        {
            this.account = account; this.password = password; this.UID = UID; this.GID = GID; this.fullname = fullname; this.office = office;
            this.extension = extension; this.homephone = homephone; this.email = email; this.directory = directory; this.shell = shell;
        }
        public override string ToString()
        {
            var gecos = string.Join(",", new string[] { fullname, office, extension, homephone, email });
            return string.Join(":", new string[] { account, password, UID.ToString(), GID.ToString(), gecos, directory, shell });
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            var jsmith = new PasswordRecord("jsmith", "x", 1001, 1000, "Joe Smith", "Room 1007", "(234)555-8917", "(234)555-0077", "jsmith@rosettacode.org", 
                "/home/jsmith", "/bin/bash");
            var jdoe = new PasswordRecord("jdoe", "x", 1002, 1000, "Jane Doe", "Room 1004", "(234)555-8914", "(234)555-0044", "jdoe@rosettacode.org", "/home/jdoe", 
                "/bin/bash");
            var xyz = new PasswordRecord("xyz", "x", 1003, 1000, "X Yz", "Room 1003", "(234)555-8913", "(234)555-0033", "xyz@rosettacode.org", "/home/xyz", "/bin/bash");

            // Write these records out in the typical system format. 
            File.WriteAllLines("passwd.txt", new string[] { jsmith.ToString(), jdoe.ToString() });

            // Append a new record to the file and close the file again.
            File.AppendAllText("passwd.txt", xyz.ToString());

            // Open the file and demonstrate the new record has indeed written to the end.
            string[] lines = File.ReadAllLines("passwd.txt");
            Console.WriteLine("Appended record: " + lines[2]);
        }
    }
}

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