Adding strings to a RichTextBox in C#

Question

I currently have a function that will set a value to a RichTextBox, although how could you "add" a value or a new line to it, rather than overwriting existing data in the RichTextBox?

richTextBox2.Text = DateTime.Today + " Hello";

Solution 1

richTextBox2.AppendText(Environment.NewLine + DateTime.Today + " Hello"); 

Solution 2

richTextBox2.AppendText(String.Format("{0} the date is {1}{2}", "Hello", DateTime.Today, Environment.NewLine));

Please don't use +

Solution 3

richTextBox2.Document.Blocks.Clear();
richTextBox2.Document.Blocks.Add(new Paragraph(new Run("string")));

Comments

[abatishchev]

James, I recommend you to use a single OpenId to log in, so you will be the same user as usually

[James Buttler]

@abatishchev There is more than one function adding text to this, hence I don't think your solution would work

[David Heffernan]

This is going to be horribly inefficient when there is a lot of text in the control

[abatishchev]

@David: Nothing said in the answer about a lot of text

[David Heffernan]

reading the entire contents of the control just to add another line of text is very inefficient. Why go out of your way to write inefficient code?

[abatishchev]

@David: Does RichTextBox.Text property read entire control content rather than holds it into a variable? I didn't knew that.

[David Heffernan]

It's just a wrapper around the Windows control I expect and the Windows control holds the text. The implementation of the Text getter will send a message to the control to retrieve the entire text, I'd guess.

[schmijos]

Why no "+"? Just for readability? Or is there an other reason?

[0xDEADBEEF]

@JosuaSchmid strings are immutable. Using + to chain n of them (especially for big strings and/or many catenations) creates n-1 strings in memory one bigger than the last one, resulting in a (temporary) waste of memory and a lot of computing overhead. This is why using String.Format() and the StringBuilder-Class is prefered in favor of +

[user1027167]

The user asked for winforms not for WPF.