How do I include a newline character in a string in Delphi?

In the System.pas (which automatically gets used) the following is defined:

const
  sLineBreak = {$IFDEF LINUX} AnsiChar(#10) {$ENDIF} 
               {$IFDEF MSWINDOWS} AnsiString(#13#10) {$ENDIF};

This is from Delphi 2009 (notice the use of AnsiChar and AnsiString). (Line wrap added by me.)

So if you want to make your TLabel wrap, make sure AutoSize is set to true, and then use the following code:

label1.Caption := 'Line one'+sLineBreak+'Line two';

Works in all versions of Delphi since sLineBreak was introduced, which I believe was Delphi 6.

Here's an even shorter approach:

my_string := 'Hello,'#13#10' world!';

my_string := 'Hello,' + #13#10 + 'world!';

#13#10 is the CR/LF characters in decimal

On the side, a trick that can be useful:
If you hold your multiple strings in a TStrings, you just have to use the Text property of the TStrings like in the following example.

Label1.Caption := Memo1.Lines.Text;

And you'll get your multi-line label...

Or you can use the ^M+^J shortcut also. All a matter of preference. the "CTRL-CHAR" codes are translated by the compiler.

MyString := 'Hello,' + ^M + ^J + 'world!';

You can take the + away between the ^M and ^J, but then you will get a warning by the compiler (but it will still compile fine).