StringBuilder in c#

StringBuilder



The StringBuilder class (System.Text namespace) represents a mutable (editable)
string. With a StringBuilder, you can Append, Insert, Remove, and Replace substrings
without replacing the whole StringBuilder.
StringBuilder’s constructor optionally accepts an  initial string value, as well as a
starting size for its internal capacity (default is 16 characters). If you go above this,
StringBuilder  automatically  resizes  its  internal  structures  to  accommodate  (at  a
slight performance cost) up to its maximum capacity (default is int.MaxValue).
A popular use of StringBuilder  is to build up a  long string by repeatedly calling
Append. This approach is much more efficient than repeatedly concatenating ordi-
nary string types:
StringBuilder sb = new StringBuilder();
for (int i = 0; i < 50; i++) sb.Append (i + ",");
To get the final result, call ToString():
Console.WriteLine (sb.ToString());

0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,
27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,

In our example, the expression i + "," means that we’re still
repeatedly concatenating strings. However,  this  incurs only a
small performance cost in that the strings in question are small
and don’t grow with each  loop  iteration. For maximum per-
formance, however, we could change the loop body to this:
{ sb.Append (i.ToString()); sb.Append (","); }
AppendLine performs an Append that adds a new line sequence ("\r\n" in Windows).
AppendFormat accepts a composite format string, just like String.Format.
As well  as  the  Insert,  Remove,  and  Replace methods  (Replace  functions  such  as
string’s Replace), StringBuilder defines a Length property and a writable indexer for
getting/setting individual characters.
To  clear  the  contents of  a  StringBuilder,  either  instantiate  a new one or  set  its
Length to zero.


Setting a StringBuilder’s Length to zero doesn’t shrink  its  in-
ternal capacity. So, if the StringBuilder previously contained 1
million characters, it will continue to occupy around 2 MB of
memory after zeroing its Length. If you want to release the mem-
ory, you must create a new StringBuilder and allow the old one
to drop out of scope (and be garbage-collected).