HPUX DString[3]
Tcl_DStringInit(3) Tcl Tcl_DStringInit(3)
Tcl Library Procedures Tcl Library Procedures
7.0
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NAME
Tcl_DStringInit, Tcl_DStringAppend, Tcl_DStringAppendElement,
Tcl_DStringStartSublist, Tcl_DStringEndSublist, Tcl_DStringLength,
Tcl_DStringValue, Tcl_DStringTrunc, Tcl_DStringFree, Tcl_DStringResult
- manipulate dynamic strings
SYNOPSIS
#include <tcl.h>
Tcl_DStringInit(dsPtr)
char *
Tcl_DStringAppend(dsPtr, string, length)
char *
Tcl_DStringAppendElement(dsPtr, string)
Tcl_DStringStartSublist(dsPtr)
Tcl_DStringEndSublist(dsPtr)
int
Tcl_DStringLength(dsPtr)
char *
Tcl_DStringValue(dsPtr)
Tcl_DStringTrunc(dsPtr, newLength)
Tcl_DStringFree(dsPtr)
Tcl_DStringResult(interp, dsPtr)
ARGUMENTS
Tcl_DString *dsPtr (in/out) Pointer to structure that is used
to manage a dynamic string.
char *string (in) Pointer to characters to add to
dynamic string.
int length (in) Number of characters from string
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
- 1 - Formatted: August 11, 1996
Tcl_DStringInit(3) Tcl Tcl_DStringInit(3)
Tcl Library Procedures Tcl Library Procedures
7.0
character.
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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 string 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 doesn't take a length argument (it appends all of string) 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_DStringAppendElement 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.
- 2 - Formatted: August 11, 1996
Tcl_DStringInit(3) Tcl Tcl_DStringInit(3)
Tcl Library Procedures Tcl Library Procedures
7.0
Tcl_DStringTrunc truncates a dynamic string to a given length. It has
no effect if the string was already smaller than newLength. This
procedure 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_DStringFree should be called when you're 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 interp->result. This saves the cost of allocating new memory
and copying the string. Tcl_DStringResult also reinitializes the
dynamic string to an empty string.
KEYWORDS
append, dynamic string, free, result
- 3 - Formatted: August 11, 1996