8.6.4 String operators

There is only one string operator : +. It's action is to concatenate the contents of the two strings (or characters) it stands between. One cannot use + to concatenate null-terminated (PChar) strings. The following are valid string operations:

  'This is ' + 'VERY ' + 'easy !'  
  Dirname+'\'

The following is not:

Var Dirname = Pchar;  
...  
  Dirname := Dirname+'\';

Because Dirname is a null-terminated string.