NAME

       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

SYNOPSIS

       #include <tcl.h>

       Tcl_DStringInit(dsPtr)

       char *
       Tcl_DStringAppend(dsPtr, bytes, length)

       char *
       Tcl_DStringAppendElement(dsPtr, element)

       Tcl_DStringStartSublist(dsPtr)

       Tcl_DStringEndSublist(dsPtr)

       int
       Tcl_DStringLength(dsPtr)

       char *
       Tcl_DStringValue(dsPtr)

       Tcl_DStringSetLength(dsPtr, newLength)

       Tcl_DStringTrunc(dsPtr, newLength)

       Tcl_DStringFree(dsPtr)

       Tcl_DStringResult(interp, dsPtr)

       Tcl_DStringGetResult(interp, dsPtr)

ARGUMENTS

       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
                                           character.

       int newLength (in)                  New length for  dynamic  string,  not  including  null
                                           terminating character.

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

DESCRIPTION

       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 assumptions 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 returns 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 converts the string to  a  proper  list
       element  before appending.  Tcl_DStringAppendElement adds a separator space before the new
       list element 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  dynamic  string  (not
       including  the  terminating  null character).  Tcl_DStringValue is a  macro that returns a
       pointer to the current contents 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 initialize 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 truncated to zero length,  so  Tcl_DStringFree  will  still  need  to  be
       called.

       Tcl_DStringTrunc  changes  the  length  of  a  dynamic  string.   This  procedure  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 dynamic 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 result.  If possible it does this by moving
       a pointer rather than by copying the string.

KEYWORDS

       append, dynamic string, free, result