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Tcl_DString(3)		    Tcl	Library	Procedures		Tcl_DString(3)


       Tcl_DStringInit,	     Tcl_DStringAppend,	     Tcl_DStringAppendElement,
       Tcl_DStringStartSublist,	  Tcl_DStringEndSublist,    Tcl_DStringLength,
       Tcl_DStringValue,	Tcl_DStringSetLength,	     Tcl_DStringTrunc,
       Tcl_DStringFree,	Tcl_DStringResult, Tcl_DStringGetResult	 -  manipulate
       dynamic strings

       #include	<tcl.h>


       char *
       Tcl_DStringAppend(dsPtr,	bytes, length)

       char *
       Tcl_DStringAppendElement(dsPtr, element)




       char *

       Tcl_DStringSetLength(dsPtr, newLength)

       Tcl_DStringTrunc(dsPtr, newLength)


       Tcl_DStringResult(interp, dsPtr)

       Tcl_DStringGetResult(interp, dsPtr)

       Tcl_DString *dsPtr (in/out)	   Pointer  to	structure that is used
					   to manage a dynamic string.

       const char *bytes (in)		   Pointer to characters to append  to
					   dynamic string.

       const char *element (in)		   Pointer  to characters to append as
					   list	element	to dynamic string.

       int length (in)			   Number of bytes from	bytes  to  add
					   to  dynamic string.	If -1, add all
					   characters up to  null  terminating

       int newLength (in)		   New	length for dynamic string, not
					   including null terminating  charac-

       Tcl_Interp *interp (in/out)	   Interpreter	whose  result is to be
					   set from or moved  to  the  dynamic

       Dynamic	strings	 provide  a mechanism for building up arbitrarily long
       strings by gradually appending information.  If the dynamic  string  is
       short  then there will be no memory allocation overhead;	 as the	string
       gets larger, additional space will be allocated as needed.

       Tcl_DStringInit initializes a  dynamic  string  to  zero	 length.   The
       Tcl_DString  structure  must have been allocated	by the caller.	No as-
       sumptions are made about	the current state of the  structure;  anything
       already in it is	discarded.  If the structure has been used previously,
       Tcl_DStringFree should be called	first to free up any memory  allocated
       for the old string.

       Tcl_DStringAppend  adds new information to a dynamic string, allocating
       more memory for the string if needed.  If length	is less	than zero then
       everything  in  bytes  is  appended  to	the dynamic string;  otherwise
       length specifies	the number of bytes to append.	Tcl_DStringAppend  re-
       turns  a	 pointer  to the characters of the new string.	The string can
       also be retrieved from the string field of the Tcl_DString structure.

       Tcl_DStringAppendElement	is similar to Tcl_DStringAppend	except that it
       does not	take a length argument (it appends all of element) and it con-
       verts  the  string  to  a  proper  list	 element   before   appending.
       Tcl_DStringAppendElement	adds a separator space before the new list el-
       ement unless the	new list element is the	first in a  list  or  sub-list
       (i.e.  either  the  current  string is empty, or	it contains the	single
       character "{", or the last two characters of the	current	string	are  "
       {").   Tcl_DStringAppendElement	returns	a pointer to the characters of
       the new string.

       Tcl_DStringStartSublist and Tcl_DStringEndSublist can be	used to	create
       nested lists.  To append	a list element that is itself a	sublist, first
       call Tcl_DStringStartSublist, then  call	 Tcl_DStringAppendElement  for
       each of the elements in the sublist, then call Tcl_DStringEndSublist to
       end the sublist.	 Tcl_DStringStartSublist appends a space character  if
       needed,	followed  by  an  open brace;  Tcl_DStringEndSublist appends a
       close brace.  Lists can be nested to any	depth.

       Tcl_DStringLength is a macro that returns the current length of	a  dy-
       namic   string	(not   including   the	terminating  null  character).
       Tcl_DStringValue	is a  macro that returns a pointer to the current con-
       tents of	a dynamic string.

       Tcl_DStringSetLength  changes  the  length  of  a  dynamic  string.  If
       newLength is less than the string's current length, then	the string  is
       truncated.   If	newLength is greater than the string's current length,
       then the	string will become longer and new space	will be	allocated  for
       the  string if needed.  However,	Tcl_DStringSetLength will not initial-
       ize the new space except	to provide a terminating null  character;   it
       is  up  to  the	caller to fill in the new space.  Tcl_DStringSetLength
       does not	free up	the string's storage space even	if the string is trun-
       cated to	zero length, so	Tcl_DStringFree	will still need	to be called.

       Tcl_DStringTrunc	 changes  the length of	a dynamic string.  This	proce-
       dure is now deprecated.	Tcl_DStringSetLength  should be	used instead.

       Tcl_DStringFree should be  called  when	you  are  finished  using  the
       string.	 It  frees up any memory that was allocated for	the string and
       reinitializes the string's value	to an empty string.

       Tcl_DStringResult sets the result of interp to the value	of the dynamic
       string  given by	dsPtr.	It does	this by	moving a pointer from dsPtr to
       the interpreter's result.  This saves the cost of allocating new	memory
       and  copying  the string.  Tcl_DStringResult also reinitializes the dy-
       namic string to an empty	string.

       Tcl_DStringGetResult does the opposite of Tcl_DStringResult.   It  sets
       the  value  of dsPtr to the result of interp and	it clears interp's re-
       sult.  If possible it does this by moving  a  pointer  rather  than  by
       copying the string.

       append, dynamic string, free, result

Tcl				      7.4			Tcl_DString(3)


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