Adding Text to a TextBox multiple times from code behind?

Question

I'm still stuck... I'm using ASP.NET Web Forms.

I have a TextBox:

<p><asp:TextBox runat="server" TextMode="Multiline" ReadOnly="true" ID="txtBoxAlgo" rows="50" width="878px"></asp:TextBox></p>

I can only add text to this textbox Once from the code behind:

txtBoxAlgo.Text = ("My first line of text" + Environment.NewLine);

Now my issue is if I try to add text again to the textbox nothing happens. For example:

txtBoxAlgo.Text = ("First try! It works!");
txtBoxAlgo.Text = ("Nothing, not working :(");

Now I'm moving over a simple program I have made for a C# console and C# Windows forms. I'm experimenting with ASP.NET Web Forms.

I used Console.WriteLine(""); throughout my console application. The only way I can do something similar for webforms is make Labels and TextBoxes+Multilines for each instance I wanto output text to the screen, which at this point is not worth doing all that effort for each instance of Console.WriteLine.

I tried Response.Write, but first off this shows in the top left corner of the webpage and its all unformatted.

I have ran out of ideas and I can't find anything while searching. Can you add or Append text to a textbox? Can we use Response.Write in some type of way to format everything so a user can read it?

By nothing happens, you mean the text doesn't change from "My first line of text", right? How are you attempting to change the text change after that? With a button? Also, by adding text again you mean, concatenate or replace? Because Text = "" is replacing — Fenrir88
The TextBox stays: "First ty! It works!". even after the second line of code that is suppose to add or change to "Nothing, not working:(" ReadOnly="false" fixed the update issue, my problem still is the textbox now only shows the last Text = ""; Is there anyway to add text to a new line while keeping the old text? — 702cs
@702cs i noticed this same issue with a question you asked yesterday. when adding additional text to a Textbox, you have to use Textbox1.Text += "Additional Text"; .. — terbubbs
@702cs or you can use StringBuilder just like I showed yesterday — terbubbs

terbubbs terbubbs · Accepted Answer · 2016-03-31T17:21:48

Use += instead of = when appending extra text to your Textbox

txtBoxAlgo.Text = "My first line of text" + Environment.NewLine;
txtBoxAlgo.Text += "First try! It works!";
txtBoxAlgo.Text += "Should work.";

Every time you use = when assigning a value to your Textbox, you are just replacing the previous value which is why only the last string is visible.

Or use StringBuilder:

StringBuilder sb = new StringBuilder();
sb.AppendLine("First Line");
sb.AppendLine("Second Line");
txtBoxAlgo.Text = sb.ToString();

Adding Text to a TextBox multiple times from code behind?

1 Answers