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.
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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

Tcl                                                    7.4                                     Tcl_DString(3tcl)