How to add a line to a multiline TextBox

Question

How can i add a line of text to a multi-line TextBox   e g  pseudocode   textBox1 Clear    textBox1 Lines Add  1000     textBox1 Lines Add  750-999    textBox1 Lines Add  400-749       snip    textBox1 Lines Add  40-59      or  textBox1 Lines Append  brown    textBox1 Lines Append  brwn    textBox1 Lines Append  brn    textBox1 Lines Append  brow    textBox1 Lines Append  br    textBox1 Lines Append  brw    textBox1 Lines Append  brwm    textBox1 Lines Append  bron    textBox1 Lines Append  bwn    textBox1 Lines Append  brnw    textBox1 Lines Append  bren    textBox1 Lines Append  broe    textBox1 Lines Append  bewn      The only methods that TextBox Lines implements  that i can see  are    Clone CopyTo Equals GetType GetHashCode GetEnumerator Initialize GetLowerBound GetUpperBound GetLength GetLongLength GetValue SetValue ToString

User · Answer

I would go with the System Environment NewLine or a StringBuilder  Then you could add lines with a string builder like this        StringBuilder sb   new StringBuilder    sb AppendLine  brown    sb AppendLine  brwn     textbox1 Text    sb ToString      or NewLine like this   textbox1 Text    System Environment NewLine    brown     Better   StringBuilder sb   new StringBuilder textbox1 Text   sb AppendLine  brown    sb AppendLine  brwn     textbox1 Text   sb ToString

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The adding of Environment NewLine or  r n was not working for me  initially  with my textbox   I found I had forgotten to go into the textbox s Behavior properties and set the  Multiline  property to  True  for it to add the lines   I just thought I d add this caveat since no one else did in the answers  above  and I had thought the box was just going to auto-expand and forgot I needed to actually set the Mulitline property for it to work   I know it s sort of a bonehead thing  which is the kind of thing that happens to us late on a Friday afternoon   but it might help someone remember to check that   Also  in the Appearance section is the  ScrollBars  property that I needed to set to  Both   to get both horizontal and vertical bars so that text could actually be scrolled and seen in its entirety   So the answer here isn t just a code one by appending Environment NewLine or  r n to the  Text  but also make sure your box is set up properly with the right properties

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Casperah pointed out that i m thinking about it wrong   A TextBox doesn t have lines it has text that text can be split on the CRLF into lines  if requested but there is no notion of lines  The question then is how to accomplish what i want  rather than what WinForms lets me  There are subtle bugs in the other given variants   textBox1 AppendText  quot Hello quot    Environment NewLine   textBox1 AppendText  quot Hello quot     quot  r n quot    textBox1 Text     quot Hello r n quot  textbox1 Text    System Environment NewLine    quot brown quot    They either append or prepend a newline when one  might  not be required  So  extension helper  public static class WinFormsExtensions      public static void AppendLine this TextBox source  string value             if  source Text Length  0           source Text   value        else          source AppendText  quot  r n quot  value           So now  textBox1 Clear    textBox1 AppendLine  quot red quot    textBox1 AppendLine  quot green quot    textBox1 AppendLine  quot blue quot     and textBox1 AppendLine String Format  quot Processing file  0  quot   filename     Note  Any code is released into the public domain  No attribution required

User · Answer

Above methods did not work for me  I got the following exception   Exception    System InvalidOperationException  in System Windows Forms dll   Turns out I needed to call Invoke on my controls first  See answer here

User · Answer

If you know how many lines you want  create an array of String with that many members  e g  myStringArray   Then use myListBox Lines   myStringArray

User · Answer

The  Lines  property of a TextBox is an array of strings  By definition  you cannot add elements to an existing string    like you can to a List lt string gt   There is simply no method available for the purpose  You must instead create a new string   based on the current Lines reference  and assign it to Lines    Using a little Linq   NET 3 5 or later    textBox1 Lines   textBox Lines Concat new    Some Text    ToArray      This code is fine for adding one new line at a time based on user interaction  but for initializing a textbox with a few dozen new lines  it will perform very poorly  If you re setting the initial value of a TextBox  I would either set the Text property directly using a StringBuilder  as other answers have mentioned   or if you re set on manipulating the Lines property  use a List to compile the collection of values and then convert it to an array to assign to Lines   var myLines   new List lt string gt      myLines Add  brown    myLines Add  brwn    myLines Add  brn    myLines Add  brow    myLines Add  br    myLines Add  brw         textBox1 Lines   myLines ToArray      Even then  because the Lines array is a calculated property  this involves a lot of unnecessary conversion behind the scenes

User · Answer

Try this  textBox1 Text     SomeText r n     you can also try   textBox1 Text     SomeText    Environment NewLine    Where  r is carriage return and  n is new line

User · Answer

You have to use the AppendText method of the textbox directly  If you try to use the Text property  the textbox will not scroll down as new line are appended   textBox1 AppendText  Hello    Environment NewLine

User · Answer

Append a  r n to the string to put the text on a new line   textBox1 Text      brown r n    textBox1 Text      brwn      This will produce the two entries on separate lines

User · Answer

Just put a line break into your text   You don t add lines as a method  Multiline just supports the use of line breaks

[c#] How to add a line to a multiline TextBox?

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