how to edit a line from a text file using c#

Question

Hello all!

My records are in a text file format.  I need to update a line from that text file using C#, how do I do that?  I'm new with C# so any suggestion will be greatly appreciated...

 

 

Answer 1

System.IO.File.ReadAllLines and System.IO.File.WriteAllLines is your best bet, then you can read the file in, find the line and change it, then write it again.  You cannot change a line in a file, you need to read it all, change it and write it all again.

 

Answer 2

I read the file but I need to know how to change one line of the file (really just one character).  I checked to see if s.Equals("my string") but I can't seem to figure out how to change "my string" to my String".   Any help?

 

Thanks.

Mike

Answer 3

I have the same question because i need to change a specific string inside a line in a file.ini

 

Thanks!

 

Answer 4

StringBuilder newFile = new StringBuilder();

string temp = "";

string[] file = File.ReadAllLines(@"C:\Documents and Settings\john.grove\Desktop\1.txt");

foreach (string line in file)

{

    if (line.Contains("string"))

    {

        temp = line.Replace("string", "String");

        newFile.Append(temp + "\r\n");

        continue;

    }

    newFile.Append(line + "\r\n");

}

File.WriteAllText(@"C:\Documents and Settings\john.grove\Desktop\1.txt", newFile.ToString());

Answer 5

Insert, Update, Delete in text file using c# .net Window Application


Application Name: AppSample


Form1.Designer.cs
************************

        private System.Windows.Forms.Button button4;
        private System.Windows.Forms.Button button6;
        private System.Windows.Forms.TextBox txtLastName;
        private System.Windows.Forms.TextBox txtPhone;
        private System.Windows.Forms.TextBox txtMail;
        private System.Windows.Forms.TextBox txtWeb;
        private System.Windows.Forms.TextBox txtName;
        private System.Windows.Forms.Button button1;
        private System.Windows.Forms.Label label4;
        private System.Windows.Forms.Label label5;
        private System.Windows.Forms.Label label6;
        private System.Windows.Forms.Label label7;
        private System.Windows.Forms.Label label8;
        private System.Windows.Forms.ComboBox combo;

Form1.cs
************
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace AppSample
{
    public partial class Form1 : Form
    {
        private DataText conDB;
        string txtvalue="";

        public Form1()
        {
            InitializeComponent();
            conDB = new DataText();
            conDB.Path = "C:/TextOperation.txt"; // dont use '\'!!
            fillCombo();
        }
        private void fillCombo()
        {
            this.combo.Items.Clear();
            int temp = conDB.Entries();
            if (temp > 0)
            {
                temp--;
                for (int i = 0; i <= temp; i++)
                {
                    string name = "";
                    conDB.ReadEntrie(i, ref name);
                    if (name == "")
                    {
                        name = "<empty>";
                    }
                    this.combo.Items.Add(name);
                }
                combo.SelectedIndex = 0;
            }
        }
       
        private void button6_Click(object sender, EventArgs e)
        {

            conDB.InsertEntrie(txtName.Text, txtLastName.Text,
               
            txtPhone.Text,txtMail.Text,txtWeb.Text);
            //txtID.Text = Convert.ToString(conDB.Entries()-1);
            txtvalue = Convert.ToString(conDB.Entries() - 1);
            fillCombo();
            txtName.Text = "";
            txtLastName.Text = "";
            txtPhone.Text = "";
            txtMail.Text = "";
            txtWeb.Text = "";
        }

        private void read(int id)
        {
            //txtID.Text = id.ToString();
            txtvalue = id.ToString();
            string str_name = "", str_lastname = "", str_phone = "", str_mail = "", str_web = "";

            bool result = conDB.ReadEntrie(id, ref str_name, ref str_lastname, ref str_phone, ref str_mail, ref str_web);
            txtName.Text = str_name;
            txtLastName.Text = str_lastname;
            txtPhone.Text = str_phone;
            txtMail.Text = str_mail;
            txtWeb.Text = str_web;
            if (!result) { MessageBox.Show("Invalid record"); }
        }
       

        private void button4_Click(object sender, EventArgs e)
        {
           string str_name = "", str_lastname = "", str_phone = "", str_mail = "", str_web = "";
           str_name =txtName.Text ;
           str_lastname =txtLastName.Text;
           str_phone =txtPhone.Text;
           str_mail =txtMail.Text;
           str_web =txtWeb.Text;
            //int id = Convert.ToInt32(txtID.Text);
           int id = Convert.ToInt32(txtvalue);           
           conDB.UpdateEntrie(id, str_name, str_lastname, str_phone, str_mail, str_web);
            fillCombo();
            txtName.Text = "";
            txtLastName.Text = "";
            txtPhone.Text = "";
            txtMail.Text = "";
            txtWeb.Text = "";
        }

        private void button1_Click(object sender, EventArgs e)
        {
            //int id = Convert.ToInt32(txtID.Text);
            int id = Convert.ToInt32(txtvalue);
            conDB.DeleteEntrie(id);
            read(0);
            fillCombo();
            txtName.Text = "";
            txtLastName.Text = "";
            txtPhone.Text = "";
            txtMail.Text = "";
            txtWeb.Text = "";
        }

    

        private void combo_SelectedIndexChanged(object sender, EventArgs e)
        {
            //txtID.Text = combo.SelectedIndex.ToString();
            txtvalue = combo.SelectedIndex.ToString();
            //read(Convert.ToInt32(txtID.Text));
            read(Convert.ToInt32(txtvalue));
        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

       

     
    }
}
DataText.cs
***************
using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Collections;
/*Renan Rodrigues Duarte */
/*Class for Plain Tex DataBase*/
namespace AppSample
{
    class DataText
    {

        private FileStream fs = null;
        private StreamReader sr = null;
        private StreamWriter sw = null;

        private string data_path = "";
        /// <summary>
        /// Get or Set the path of the text file!
        /// </summary>
        public string Path
        {
            get { return data_path; }
            set { data_path = value; }
        }
        public int Entries()
        {
            int count = 0;
            CreateConfigFile();
            try
            {
                fs = new FileStream(data_path, FileMode.Open);
                if (fs.Length >0)
                {
                    sr = new StreamReader(fs);
                    while (sr.ReadLine() != null)
                    {
                        count++;
                    }
                    sr.Close();
                }
                fs.Close();
            }
            catch
            {
                count = 0;
            }
            return count;
        }
    
        public bool ReadEntrie(int id, ref string name, ref string lastname, ref string phone, ref string mail, ref string website)
        {
            int count = 0;
            CreateConfigFile();
            try
            {
                fs = new FileStream(data_path, FileMode.Open);
                sr = new StreamReader(fs);
                string temp = "";
                bool cond = true;
                while (cond==true)
                {
                   
                    if ((temp=sr.ReadLine()) == null)
                    {
                        sr.Close();
                        fs.Close();
                        cond = false;
                        if (count==0)
                        return false;
                    }
                   

                    if (count == id)
                    {
                        string[] stringSplit = temp.Split('\t');
                        int _maxIndex = stringSplit.Length;
                        name = stringSplit[0];
                        lastname = stringSplit[1];
                        phone = stringSplit[2];
                        mail = stringSplit[3];
                        website = stringSplit[4];

                    }
                    count++;
                   
                }
               
                sr.Close();
                fs.Close();
                return true;
            }
            catch
            {
                return false;
            }

        }
        public bool ReadEntrie(int id, ref string name)
        {
            int count = 0;
            CreateConfigFile();
            try
            {
                fs = new FileStream(data_path, FileMode.Open);
                sr = new StreamReader(fs);
                bool cond = true;
                string temp = "";
                while (cond == true)
                {

                    if ((temp = sr.ReadLine()) == null)
                    {
                        sr.Close();
                        fs.Close();
                        cond = false;
                        if (count == 0)
                            return false;
                    }

                    if (count == id)
                    {
                        string[] stringSplit = temp.Split('\t');
                        int _maxIndex = stringSplit.Length;
                        name = stringSplit[0];
                    }
                    count++;

                }

                sr.Close();
                fs.Close();
                return true;
            }
            catch
            {
                return false;
            }

        }
        public bool InsertEntrie(string name, string lastname, string phone, string mail, string website)
        {
            CreateConfigFile();
            try
            {
                fs = new FileStream(data_path, FileMode.Append);
                sw = new StreamWriter(fs);
                //sw.WriteLine(name + ";" + lastname + ";" + phone + ";" + mail + ";" + website);
                sw.WriteLine(name + '\t' + lastname + '\t'+ phone + '\t' + mail + '\t' + website);
                sw.Close();
                fs.Close();
                return true;
            }
            catch(Exception ee)
            {
                string temp = ee.Message;
                return false;
            }
        }
        public bool UpdateEntrie(int id, string name, string lastname, string phone, string mail, string website)
        {
            int count = 0;
            CreateConfigFile();
            try
            {
                fs = new FileStream(data_path, FileMode.Open);
                sr = new StreamReader(fs);

                string temp = "";
                string temp2 = "";
                while ((temp = sr.ReadLine()) != null)
                {

                    if (count == id)
                    {
                        temp2 += name + '\t' + lastname + '\t' + phone + '\t' + mail + '\t' + website + "\r\n";
                    }
                    else
                    {
                        temp2 += (temp +"\r\n");
                    }
                    count++;

                }
                sr.Close();
                fs.Close();

                fs = new FileStream(data_path, FileMode.Create);
                sw = new StreamWriter(fs);
                sw.Write(temp2);
                sw.Close();
                fs.Close();
                return true;
            }
            catch
            {
                return false;
            }
        }
        public bool DeleteEntrie(int id)
        {
            int count = 0;
            CreateConfigFile();
            try
            {
                fs = new FileStream(data_path, FileMode.Open);
                sr = new StreamReader(fs);

                string temp = "";
                string temp2 = "";
                while ((temp = sr.ReadLine()) != null)
                {

                    if (count != id)
                    {
                        temp2 += (temp + "\r\n");
                    }
                    count++;

                }
                sr.Close();
                fs.Close();

                fs = new FileStream(data_path, FileMode.Create);
                sw = new StreamWriter(fs);
                sw.Write(temp2);
                sw.Close();
                fs.Close();
                return true;
            }
            catch
            {
                return false;
            }
        }
        private bool CreateConfigFile()
        {
            try
            {
                data_path = data_path.Replace((char)92, '/');
                data_path = data_path.Replace((char)9, '/');
                if (!File.Exists(data_path))
                {

                    string temp = System.IO.Path.GetDirectoryName(data_path);
    
                    if (!Directory.Exists(temp))
                    {
                        Directory.CreateDirectory(temp);
                    }
                    fs = new FileStream(data_path, FileMode.CreateNew);
                    fs.Close();
                }
                return true;
            }
            catch //(Exception ee)
            {
                return false;
            }
        }

    }
}
Thanks,
S.S.Sivaprasad

Answer 6

this is exactly what i need.

thanks
Raj

Answer 7

Excellent...

Answer 8

This consumes too much memory.

Answer 9

This consumes too much memory.

My file has special charectors like -,_,.......So while writing back to a different file my data is being modified.

Can someone suggest me a way in which I do not need to modify more that what I need to. Say only a word

I need to modify and am writing the whole file all together. So can any body suggest me a way to do it.

Answer 10

Hello JonnGrove

Thanks ,I am using your Code Its Realy Working Good. 

Answer 11

i just start working in C#, m doing self study as my institute not offering this course,,,

i have a problem while i making a calculator in C#,

when i press the buton 2 ,, value of this button 2 prints but in this following format,

System.Windows.Forms.TextBox, Text: 2

so any1 can resolve my problem?

Answer 12

hey .. heres a smiple way using File.ReadAllLines  and  File.WriteAllLines 
make a form with 2 textbox and 2 buttons   
txt1 will contain  a record to be added
txt2 will contain a record to be removed if exists 

    TextWriter writer;
    TextReader reader;
    public Form1()
    {
      InitializeComponent();      
    }

    private void Add_btn_Click(object sender, EventArgs e)
    {
      reader = new StreamReader(File.OpenRead(@"C:\FriendLy\test.txt"));
      String line;
      while ((line = reader.ReadLine()) != null)
      { }
      reader.Close();

      writer = new StreamWriter(File.Open(@"C:\FriendLy\test.txt", FileMode.Append, FileAccess.Write));
      writer.WriteLine(txt1.Text);
      writer.Close();     
    }

    private void Remove_btn_Click(object sender, EventArgs e)
    {
      string [] _lines = File.ReadAllLines(@"C:\FriendLy\test.txt");
      string _search = txt2.Text;
      string [] new_lines = new string[_lines.Length-1];
      bool found = false;
      int i ;
      for(i = 0 ; i < _lines.Count() && !found ; i++ )
      {
        if (_lines[i].Equals(_search))
        {
          found = true ;
        }
        new_lines[i] = _lines[i];
      }
      if (!found)
      {
        return;
      }
      
      int j; 
      for (j = i+1; j < _lines.Count(); j++)
      {
        new_lines[j-1] = _lines[j];
      }            
      File.WriteAllLines(@"C:\FriendLy\test.txt",new_lines); 

    }

  }

Answer 13

Easy way to replace some text in a textfile.

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

namespace ChangeTextInFiles
{
    class Program
    {
        static void Main(string[] args) {

        /// Replaces text in a file.

        string filePath = @"c:\Windows\textfile.txt";
        string searchText = "exempleToReplace";
        string replaceText = "rePlaceByThis";
        ReplaceInFile(filePath, searchText, replaceText);
        }

        static public void ReplaceInFile(string filePath, string searchText, string replaceText)
        {

            StreamReader reader = new StreamReader(filePath);
            string content = reader.ReadToEnd();
            reader.Close();

            content = Regex.Replace(content, searchText, replaceText);

            StreamWriter writer = new StreamWriter(filePath);
            writer.Write(content);
            writer.Close();
        }
    }
}