NAME

       Tcl_NewByteArrayObj,  Tcl_SetByteArrayObj,  Tcl_GetByteArrayFromObj,  Tcl_SetByteArrayLength - manipulate
       Tcl objects as a arrays of bytes

SYNOPSIS

       #include <tcl.h>

       Tcl_Obj *
       Tcl_NewByteArrayObj(bytes, length)

       void
       Tcl_SetByteArrayObj(objPtr, bytes, length)

       unsigned char *
       Tcl_GetByteArrayFromObj(objPtr, lengthPtr)

       unsigned char *
       Tcl_SetByteArrayLength(objPtr, length)

ARGUMENTS

       const unsigned char *bytes (in)              The array of bytes used to initialize or  set  a  byte-array
                                                    object.

       int length (in)                              The length of the array of bytes.  It must be >= 0.

       Tcl_Obj *objPtr (in/out)                     For  Tcl_SetByteArrayObj,  this  points  to the object to be
                                                    converted to byte-array type.   For  Tcl_GetByteArrayFromObj
                                                    and  Tcl_SetByteArrayLength,  this points to the object from
                                                    which to get  the  byte-array  value;  if  objPtr  does  not
                                                    already  point  to a byte-array object, it will be converted
                                                    to one.

       int *lengthPtr (out)                         If non-NULL, filled with the length of the array of bytes in
                                                    the object.
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DESCRIPTION

       These procedures are used to create, modify, and read Tcl byte-array objects  from  C  code.   Byte-array
       objects  are  typically  used to hold the results of binary IO operations or data structures created with
       the binary command.  In Tcl, an array of bytes is not equivalent to a string.  Conceptually, a string  is
       an  array  of  Unicode  characters,  while  a byte-array is an array of 8-bit quantities with no implicit
       meaning.  Accessor functions are provided to get the string representation of a byte-array or to  convert
       an  arbitrary  object  to  a  byte-array.  Obtaining the string representation of a byte-array object (by
       calling Tcl_GetStringFromObj) produces a properly formed UTF-8 sequence with a one-to-one mapping between
       the bytes in the internal representation and the UTF-8 characters in the string representation.

       Tcl_NewByteArrayObj and Tcl_SetByteArrayObj will create a new object of  byte-array  type  or  modify  an
       existing  object  to  have a byte-array type.  Both of these procedures set the object's type to be byte-
       array and set the object's internal representation to a copy of  the  array  of  bytes  given  by  bytes.
       Tcl_NewByteArrayObj  returns  a  pointer  to  a  newly  allocated  object with a reference count of zero.
       Tcl_SetByteArrayObj invalidates any old string representation and, if the object is not already  a  byte-
       array object, frees any old internal representation.

       Tcl_GetByteArrayFromObj  converts  a  Tcl object to byte-array type and returns a pointer to the object's
       new internal representation as an array of bytes.  The length of this array is  stored  in  lengthPtr  if
       lengthPtr  is  non-NULL.   The  storage  for  the array of bytes is owned by the object and should not be
       freed.  The contents of the array may be modified by the caller only if the object is not shared and  the
       caller invalidates the string representation.

       Tcl_SetByteArrayLength  converts the Tcl object to byte-array type and changes the length of the object's
       internal representation as an array of bytes.  If length is greater than the  space  currently  allocated
       for  the  array,  the array is reallocated to the new length; the newly allocated bytes at the end of the
       array have arbitrary values.  If length is less than the space currently allocated  for  the  array,  the
       length of array is reduced to the new length.  The return value is a pointer to the object's new array of
       bytes.

SEE ALSO

       Tcl_GetStringFromObj, Tcl_NewObj, Tcl_IncrRefCount, Tcl_DecrRefCount

KEYWORDS

       object, byte array, utf, unicode, internationalization

Tcl                                                    8.1                                Tcl_ByteArrayObj(3tcl)