StringObj
Tcl_StringObj(3) Tcl Library Procedures Tcl_StringObj(3)
______________________________________________________________________________
NAME
Tcl_NewStringObj, Tcl_NewUnicodeObj, Tcl_SetStringObj, Tcl_SetUni-
codeObj, Tcl_GetStringFromObj, Tcl_GetString, Tcl_GetUnicode, Tcl_GetU-
niChar, Tcl_GetCharLength, Tcl_GetRange, Tcl_AppendToObj, Tcl_Appen-
dUnicodeToObj, Tcl_AppendStringsToObj, Tcl_AppendStringsToObjVA,
Tcl_AppendObjToObj, Tcl_SetObjLength, Tcl_ConcatObj - manipulate Tcl
objects as strings
SYNOPSIS
#include <tcl.h>
Tcl_Obj *
Tcl_NewStringObj(bytes, length)
Tcl_Obj * |
Tcl_NewUnicodeObj(unicode, numChars) |
void
Tcl_SetStringObj(objPtr, bytes, length)
void |
Tcl_SetUnicodeObj(objPtr, unicode, numChars) |
char *
Tcl_GetStringFromObj(objPtr, lengthPtr)
char *
Tcl_GetString(objPtr)
Tcl_UniChar * |
Tcl_GetUnicode(objPtr) |
Tcl_UniChar |
Tcl_GetUniChar(objPtr, index) |
int |
Tcl_GetCharLength(objPtr) |
Tcl_Obj * |
Tcl_GetRange(objPtr, first, last) |
void
Tcl_AppendToObj(objPtr, bytes, length)
void |
Tcl_AppendUnicodeToObj(objPtr, unicode, numChars) |
void
Tcl_AppendObjToObj(objPtr, appendObjPtr)
void
Tcl_AppendStringsToObj(objPtr, string, string, ... (char *) NULL)
void
Tcl_AppendStringsToObjVA(objPtr, argList)
void
Tcl_SetObjLength(objPtr, newLength)
Tcl_Obj *
Tcl_ConcatObj(objc, objv)
ARGUMENTS
char *bytes (in) Points to the first byte of an
array of bytes used to set or
append to a string object. This
byte array may contain embedded
null bytes unless length is neg-
ative.
int length (in) The number of bytes to copy from
bytes when initializing, set-
ting, or appending to a string
object. If negative, all bytes
up to the first null are used.
Tcl_UniChar *unicode (in) Points to the first byte of an
array of Unicode characters used
to set or append to a string
object. This byte array may
contain embedded null characters
unless numChars is negative. |
int num- |
Chars (in) | |
The number of Unicode characters |
to copy from unicode when ini- |
tializing, setting, or appending |
to a string object. If nega- |
tive, all characters up to the |
first null character are used. |
int index (in) ||
The index of the Unicode charac- |
ter to return. |
int first (in) ||
The index of the first Unicode |
character in the Unicode range |
to be returned as a new object. |
int last (in) ||
The index of the last Unicode |
character in the Unicode range |
to be returned as a new object.
Tcl_Obj *objPtr (in/out) Points to an object to manipu-
late.
Tcl_Obj *appendObjPtr (in) The object to append to objPtr
in Tcl_AppendObjToObj.
int *lengthPtr (out) If non-NULL, the location where
Tcl_GetStringFromObj will store
the the length of an object's
string representation.
char *string (in) Null-terminated string value to
append to objPtr.
va_list argList (in) An argument list which must have
been initialised using
TCL_VARARGS_START, and cleared
using va_end.
int newLength (in) New length for the string value
of objPtr, not including the
final NULL character.
int objc (in) The number of elements to con-
catenate.
Tcl_Obj *objv[] (in) The array of objects to concate-
nate.
_________________________________________________________________
DESCRIPTION
The procedures described in this manual entry allow Tcl objects to be
manipulated as string values. They use the internal representation of
the object to store additional information to make the string manipula-
tions more efficient. In particular, they make a series of append
operations efficient by allocating extra storage space for the string
so that it doesn't have to be copied for each append. Also, indexing |
and length computations are optimized because the Unicode string repre- |
sentation is calculated and cached as needed.
Tcl_NewStringObj and Tcl_SetStringObj create a new object or modify an |
existing object to hold a copy of the string given by bytes and length. |
Tcl_NewUnicodeObj and Tcl_SetUnicodeObj create a new object or modify |
an existing object to hold a copy of the Unicode string given by uni- |
code and numChars. Tcl_NewStringObj and Tcl_NewUnicodeObj return a |
pointer to a newly created object with reference count zero. All four |
procedures set the object to hold a copy of the specified string. |
Tcl_SetStringObj and Tcl_SetUnicodeObj free any old string representa- |
tion as well as any old internal representation of the object.
Tcl_GetStringFromObj and Tcl_GetString return an object's string repre-
sentation. This is given by the returned byte pointer and (for
Tcl_GetStringFromObj) length, which is stored in lengthPtr if it is
non-NULL. If the object's UTF string representation is invalid (its
byte pointer is NULL), the string representation is regenerated from
the object's internal representation. The storage referenced by the
returned byte pointer is owned by the object manager and should not be
modified by the caller. The procedure Tcl_GetString is used in the
common case where the caller does not need the length of the string
representation.
Tcl_GetUnicode returns an object's value as a Unicode string. |
Tcl_GetUniChar returns the index'th character in the object's Unicode |
representation. |
Tcl_GetRange returns a newly created object comprised of the characters |
between first and last (inclusive) in the object's Unicode representa- |
tion. If the object's Unicode representation is invalid, the Unicode |
representation is regenerated from the object's string representation. |
Tcl_GetCharLength returns the number of characters (as opposed to |
bytes) in the string object. |
Tcl_AppendToObj appends the data given by bytes and length to the |
string representation of the object specified by objPtr. If the object |
has an invalid string representation, then an attempt is made to con- |
vert bytes is to the Unicode format. If the conversion is successful, |
then the converted form of bytes is appended to the object's Unicode |
representation. Otherwise, the object's Unicode representation is |
invalidated and converted to the UTF format, and bytes is appended to |
the object's new string representation. |
Tcl_AppendUnicodeToObj appends the Unicode string given by unicode and |
numChars to the object specified by objPtr. If the object has an |
invalid Unicode representation, then unicode is converted to the UTF |
format and appended to the object's string representation. Appends are |
optimized to handle repeated appends relatively efficiently (it |
overallocates the string or Unicode space to avoid repeated realloca- |
tions and copies of object's string value). |
Tcl_AppendObjToObj is similar to Tcl_AppendToObj, but it appends the |
string or Unicode value (whichever exists and is best suited to be |
appended to objPtr) of appendObjPtr to objPtr.
Tcl_AppendStringsToObj is similar to Tcl_AppendToObj except that it can
be passed more than one value to append and each value must be a null-
terminated string (i.e. none of the values may contain internal null
characters). Any number of string arguments may be provided, but the
last argument must be a NULL pointer to indicate the end of the list.
Tcl_AppendStringsToObjVA is the same as Tcl_AppendStringsToObj except
that instead of taking a variable number of arguments it takes an argu-
ment list.
The Tcl_SetObjLength procedure changes the length of the string value
of its objPtr argument. If the newLength argument is greater than the
space allocated for the object's string, then the string space is real-
located and the old value is copied to the new space; the bytes between
the old length of the string and the new length may have arbitrary val-
ues. If the newLength argument is less than the current length of the
object's string, with objPtr->length is reduced without reallocating
the string space; the original allocated size for the string is
recorded in the object, so that the string length can be enlarged in a
subsequent call to Tcl_SetObjLength without reallocating storage. In
all cases Tcl_SetObjLength leaves a null character at
objPtr->bytes[newLength].
The Tcl_ConcatObj function returns a new string object whose value is
the space-separated concatenation of the string representations of all
of the objects in the objv array. Tcl_ConcatObj eliminates leading and
trailing white space as it copies the string representations of the
objv array to the result. If an element of the objv array consists of
nothing but white space, then that object is ignored entirely. This
white-space removal was added to make the output of the concat command
cleaner-looking. Tcl_ConcatObj returns a pointer to a newly-created
object whose ref count is zero.
SEE ALSO
Tcl_NewObj, Tcl_IncrRefCount, Tcl_DecrRefCount
KEYWORDS
append, internal representation, object, object type, string object,
string type, string representation, concat, concatenate, unicode
Tcl 8.1 Tcl_StringObj(3)
