DOKK / manpages / debian 11 / tcl8.6-doc / Tcl_GetByteArrayFromObj.3tcl.en
Tcl_ByteArrayObj(3tcl) Tcl Library Procedures Tcl_ByteArrayObj(3tcl) 







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








#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)









  
const unsigned char *bytes (in)

  
The array of bytes used to initialize or set a byte-array value. May be
      NULL even if length is non-zero.

  
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 value to be converted
      to byte-array type. For Tcl_GetByteArrayFromObj and
      Tcl_SetByteArrayLength, this points to the value from which to get
      the byte-array value; if objPtr does not already point to a
      byte-array value, it will be converted to one.

  
int *lengthPtr (out)

  
If non-NULL, filled with the length of the array of bytes in the value.
    
    

    

  










These procedures are used to create, modify, and read Tcl
    byte-array values from C code. Byte-array values 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 value to a byte-array. Obtaining the
    string representation of a byte-array value (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 value of byte-array type or modify an existing value to have a
    byte-array type. Both of these procedures set the value's type to be
    byte-array and set the value's internal representation to a copy of the
    array of bytes given by bytes. Tcl_NewByteArrayObj returns a
    pointer to a newly allocated value with a reference count of zero.
    Tcl_SetByteArrayObj invalidates any old string representation and, if
    the value is not already a byte-array value, frees any old internal
    representation. If bytes is NULL then the new byte array contains
    arbitrary values.


Tcl_GetByteArrayFromObj converts a Tcl value to byte-array
    type and returns a pointer to the value'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 value and should not be freed. The contents of the array may be modified
    by the caller only if the value is not shared and the caller invalidates the
    string representation.


Tcl_SetByteArrayLength converts the Tcl value to byte-array
    type and changes the length of the value'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 value's new array of bytes.










Tcl_GetStringFromObj, Tcl_NewObj, Tcl_IncrRefCount,
    Tcl_DecrRefCount










value, binary data, byte array, utf, unicode,
  internationalization







  

    8.1
    Tcl