Scroll to navigation

Tcl_ByteArrayObj(3tcl) Tcl Library Procedures Tcl_ByteArrayObj(3tcl)
 


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.
    
    

    
 

    

  




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



  

    8.1
    Tcl