1Tcl_ByteArrayObj(3) Tcl Library Procedures Tcl_ByteArrayObj(3)
2______________________________________________________________________________
6
8 Tcl_NewByteArrayObj, Tcl_SetByteArrayObj, Tcl_GetByteArrayFromObj,
9 Tcl_SetByteArrayLength - manipulate Tcl objects as a arrays of bytes
10
12 #include <tcl.h>
13 Tcl_Obj *
15 Tcl_NewByteArrayObj(bytes, length)
16 void
18 Tcl_SetByteArrayObj(objPtr, bytes, length)
19 unsigned char *
21 Tcl_GetByteArrayFromObj(objPtr, lengthPtr)
22 unsigned char *
24 Tcl_SetByteArrayLength(objPtr, length)
25
27 const unsigned char *bytes (in) The array of bytes used to
28 initialize or set a byte-
29 array object.
30 int length (in) The length of the array of
32 bytes. It must be >= 0.
33 Tcl_Obj *objPtr (in/out) For Tcl_SetByteArrayObj,
35 this points to the object
36 to be converted to byte-
37 array type. For Tcl_Get‐
38 ByteArrayFromObj and
39 Tcl_SetByteArrayLength,
40 this points to the object
41 from which to get the
42 byte-array value; if
43 objPtr does not already
44 point to a byte-array
45 object, it will be con‐
46 verted to one.
47 int *lengthPtr (out) If non-NULL, filled with
49 the length of the array of
50 bytes in the object.
51_________________________________________________________________
52
55 These procedures are used to create, modify, and read Tcl byte-array
56 objects from C code. Byte-array objects are typically used to hold the
57 results of binary IO operations or data structures created with the
58 binary command. In Tcl, an array of bytes is not equivalent to a
59 string. Conceptually, a string is an array of Unicode characters,
60 while a byte-array is an array of 8-bit quantities with no implicit
61 meaning. Accessor functions are provided to get the string representa‐
62 tion of a byte-array or to convert an arbitrary object to a byte-array.
63 Obtaining the string representation of a byte-array object (by calling
64 Tcl_GetStringFromObj) produces a properly formed UTF-8 sequence with a
65 one-to-one mapping between the bytes in the internal representation and
66 the UTF-8 characters in the string representation.
67 Tcl_NewByteArrayObj and Tcl_SetByteArrayObj will create a new object of
69 byte-array type or modify an existing object to have a byte-array type.
70 Both of these procedures set the object's type to be byte-array and set
71 the object's internal representation to a copy of the array of bytes
72 given by bytes. Tcl_NewByteArrayObj returns a pointer to a newly allo‐
73 cated object with a reference count of zero. Tcl_SetByteArrayObj
74 invalidates any old string representation and, if the object is not
75 already a byte-array object, frees any old internal representation.
76 Tcl_GetByteArrayFromObj converts a Tcl object to byte-array type and
78 returns a pointer to the object's new internal representation as an
79 array of bytes. The length of this array is stored in lengthPtr if
80 lengthPtr is non-NULL. The storage for the array of bytes is owned by
81 the object and should not be freed. The contents of the array may be
82 modified by the caller only if the object is not shared and the caller
83 invalidates the string representation.
84 Tcl_SetByteArrayLength converts the Tcl object to byte-array type and
86 changes the length of the object's internal representation as an array
87 of bytes. If length is greater than the space currently allocated for
88 the array, the array is reallocated to the new length; the newly allo‐
89 cated bytes at the end of the array have arbitrary values. If length
90 is less than the space currently allocated for the array, the length of
91 array is reduced to the new length. The return value is a pointer to
92 the object's new array of bytes.
93
96 Tcl_GetStringFromObj, Tcl_NewObj, Tcl_IncrRefCount, Tcl_DecrRefCount
97
100 object, byte array, utf, unicode, internationalization
101Tcl 8.1 Tcl_ByteArrayObj(3)