Find text in .txt file replace with nothing (remove line)

Question

Hello there guys...

I have a text file called online.txt.

each time the program executes, it will append a new line of text. works 100%.

Now, what I am trying to acomplish, is: Everytime the program closes I want to replace _user with an empty line.

When I say empty line, I mean the line doesn't exist...

I tryed this: Doesnt work.

try

{

this.EndInvoke(this.BeginInvoke(new MethodInvoker(delegate()

{

String strxFile = File.ReadAllText("online.txt");

strxFile = strxFile.Replace(_user, null);

File.WriteAllText("online.txt", strxFile);

})));

}

catch

{ }

I tryed this too: strxFile = strxFile.Replace(_user, "");

Doesnt work... both commands above will leave the line existing, with no string in it..

The real story is, I want to delete the line 100% like the line is not there.

Thanks Guys.

Vulpes · Answer

If you're using .NET 2.0 then this should work: string[] lines = File.ReadAllLines(online.txt); List list = new List (); foreach(string line in lines) { if (line != _user) list.Add(line); } File.WriteAllLines(online.txt list.ToArray());

Vulpes · Answer

Using LINQ you should be able to do it as follows: var lines = File.ReadAllLines(online.txt).Where (line => line != _user); File.WriteAllLines(online.txt lines.ToArray());

thiago costa · Answer

Thanks for the lesson man ! Now my software is 100% done thanks to you ! At work we have a windows 2003 server work station where all emplyees are connected to As you probably already know windows server 2003 allows multiple people to connect remotely to it at the same time... So yeah this is the local chat tool I developed it requires no internet connectiosn but all people remotely connect to the server can use it !!! using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Text; using System.Windows.Forms; using System.Timers; using System.IO; //using System.Drawing; namespace CC { public partial class Form1 : Form { public Form1() { InitializeComponent(); } //public string BalloonTipText; private void SetBalloonTip() { notifyIcon1.Icon = SystemIcons.Asterisk; notifyIcon1.BalloonTipTitle = NEW MESSAGE; notifyIcon1.BalloonTipText = A new message has arrived.; notifyIcon1.BalloonTipIcon = ToolTipIcon.Info; //this.Click += new EventHandler(Form1_Click); //this.Activated += new EventHandler(Form1_Click); //Form1_Click(EventArgs e); _showmenu(); } void _showmenu() { notifyIcon1.Visible = true; notifyIcon1.ShowBalloonTip(10000); } void Form1_Click(object sender EventArgs e) { notifyIcon1.Visible = true; notifyIcon1.ShowBalloonTip(5000); } //Ok lets do this... private static System.Timers.Timer TT1; private static System.Timers.Timer TT2; private static System.Timers.Timer TT3; private static System.Timers.Timer TT4; string _nmsg =0; //string regMatch = ; private void Form1_Load(object sender EventArgs e) { //-------------------------------------------------- //------------------------------------------------ try { this.EndInvoke(this.BeginInvoke(new MethodInvoker(delegate() { StreamWriter userwriter; userwriter = File.AppendText(online.txt); userwriter.WriteLine(_user); userwriter.Close(); }))); } catch { MessageBox.Show(cannot write user); } try { TT3 = new System.Timers.Timer(10000); TT3.Elapsed += new ElapsedEventHandler(_event3); TT3.Interval = 10000; TT3.Enabled = true; } catch { } try { TT4 = new System.Timers.Timer(5000); TT4.Elapsed += new ElapsedEventHandler(_event4); TT4.Interval = 2; TT4.Enabled = true; } catch { } try { TT1 = new System.Timers.Timer(5000); TT1.Elapsed += new ElapsedEventHandler(_event1); TT1.Interval = 2; TT1.Enabled = true; } catch { } try { TT2 = new System.Timers.Timer(5000); TT2.Elapsed += new ElapsedEventHandler(_event2); TT2.Interval = 7000; TT2.Enabled = true; } catch { } } private void BTNclose_Click(object sender EventArgs e) { try { string[] lines = File.ReadAllLines(online.txt); List list = new List (); foreach (string line in lines) { if (line != _user) list.Add(line); } File.WriteAllLines(online.txt list.ToArray()); } catch { } /* * * * try { this.EndInvoke(this.BeginInvoke(new MethodInvoker(delegate() { String strxFile = File.ReadAllText(online.txt); strxFile = strxFile.Replace(_user null); File.WriteAllText(online.txt strxFile); }))); } catch { } * * try { this.EndInvoke(this.BeginInvoke(new MethodInvoker(delegate() { System.IO.StreamReader sr = new System.IO.StreamReader(online.txt); string line = sr.ReadLine(); System.IO.StreamWriter sw = new System.IO.StreamWriter(online.txt); while ((line != null)) { if (!string.IsNullOrEmpty(line)) { sw.WriteLine(line); } line = sr.ReadLine(); } }))); } catch { } */ this.Close(); } private void Form1_Resize(object sender System.EventArgs e) { if (FormWindowState.Minimized == WindowState) Hide(); } private void notifyIcon1_DoubleClick(object sender System.EventArgs e) { Show(); WindowState = FormWindowState.Normal; } public void _event3(object source ElapsedEventArgs e) { try { this.EndInvoke(this.BeginInvoke(new MethodInvoker(delegate() { StreamReader xcheck = new StreamReader(xcheck.txt); TBnmsg.Text = xcheck.ReadToEnd(); xcheck.Close(); _nmsg = TBnmsg.Text; }))); if (_nmsg != 0) { if (Form.ActiveForm == this) { } else { SetBalloonTip(); } try { this.EndInvoke(this.BeginInvoke(new MethodInvoker(delegate() { /* StreamWriter streamwriter2; streamwriter2 = File.CreateText(xcheck.txt); streamwriter2.WriteLine(0); streamwriter2.Close();*/ String strFile = File.ReadAllText(xcheck.txt); strFile = strFile.Replace(1 0); File.WriteAllText(xcheck.txt strFile); }))); } catch { } } else { } } catch { } } public void _event4(object source ElapsedEventArgs e) { try { this.EndInvoke(this.BeginInvoke(new MethodInvoker(delegate() { StreamReader online = new StreamReader(online.txt); textBox1.Text = online.ReadToEnd(); online.Close(); }))); } catch { } } /* try { this.EndInvoke(this.BeginInvoke(new MethodInvoker(delegate() { //CODE HERE //CODE HERE //CODE HERE //CODE HERE //CODE HERE }))); } catch { } }*/ public void _event1(object source ElapsedEventArgs e) { try { this.EndInvoke(this.BeginInvoke(new MethodInvoker(delegate() { StreamReader STNEXUS = new StreamReader(nexus.txt); TBnexus.Text = STNEXUS.ReadToEnd(); STNEXUS.Close(); //move the caret to the end of the text TBnexus.SelectionStart = TBnexus.TextLength; //scroll to the caret TBnexus.ScrollToCaret(); }))); } catch { } } string _user = Environment.UserName; public void _event2(object source ElapsedEventArgs e) { } private void tb_KeyDown(object sender KeyEventArgs e) { if (e.KeyCode == Keys.Enter) { _enter(); } } private void _enter() { if (TBmessage.Text != ) { try { this.EndInvoke(this.BeginInvoke(new MethodInvoker(delegate() { String strFile = File.ReadAllText(xcheck.txt); strFile = strFile.Replace(0 1); File.WriteAllText(xcheck.txt strFile); }))); } catch { } try { this.EndInvoke(this.BeginInvoke(new MethodInvoker(delegate() { StreamWriter streamwriter; streamwriter = File.AppendText(nexus.txt); streamwriter.WriteLine(_user +   + TBmessage.Text + 
); streamwriter.Close(); TBmessage.Text = ; }))); } catch { } } else { MessageBox.Show(No message to sendMessage Box is EMPTY); } } private void button1_Click(object sender EventArgs e) { this.EndInvoke(this.BeginInvoke(new MethodInvoker(delegate() { StreamWriter streamwriter2; streamwriter2 = File.AppendText(xcheck.txt); streamwriter2.WriteLine(0); streamwriter2.Close(); }))); _enter(); } private void button2_Click(object sender EventArgs e) { StreamReader streamreader1 = new StreamReader(nexus.txt); TBhistory.Text = streamreader1.ReadToEnd(); streamreader1.Close(); panel2.Visible = true; BTNback.Visible = true; BTNclose.Visible = false; panel1.Visible = false; } private void BTNback_Click(object sender EventArgs e) { panel2.Visible = false; BTNback.Visible = false; BTNclose.Visible = true; panel1.Visible = true; } } }

Vulpes · Answer

Behind the scenes LINQ filter operators such as 'Where' will iterate through the collection and extract those elements which satisfy the filter condition. However LINQ uses 'deferred execution' which means that it doesn't actually do anything until the results of the query are enumerated. To achieve this it uses an iterator (introduced in .NET 2.0) and so the code will be equivalent to this: foreach(string line in lines) { if (line != _user) yield return line; }

thiago costa · Answer

WOW it works !!!!!!! Thank you so much I love you ! Question... What's the difference between using LINQ and the second example you gave me ? Is it the same exact procedure ??? Anyways . it works 100% you resolved my problem. Thanks again <3

thiago costa · Answer

Thank you for your answer I bet it works... The only problem is I am using .net framework 2.0. .net framework 2.0 does not support LINQ right ?

Find text, in .txt file, replace with nothing (remove line)