How to read from a text file into a textbox?

[IvanIvanov]

Is this correct way?


StreamReader f = new StreamReader(new FileStream("c:\afile.txt", FileMode.Open, FileAccess.ReadWrite));
char[] d = new char[????????];
f.ReadBlock (d, 0, ??????); - or maybe f.Read()?
textBox1.Text = new string(d);


All MSDN/gooogle examples talk about lines... I want read ALL text, not only one line...
How to learn the length of the text?