1Tcl_ByteArrayObj(3) Tcl Library Procedures Tcl_ByteArrayObj(3)
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6
8 Tcl_NewByteArrayObj, Tcl_SetByteArrayObj, Tcl_GetByteArrayFromObj,
9 Tcl_SetByteArrayLength - manipulate Tcl values 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 value. May be NULL
30 even if length is non-
31 zero.
32 int length (in) The length of the array of
34 bytes. It must be >= 0.
35 Tcl_Obj *objPtr (in/out) For Tcl_SetByteArrayObj,
37 this points to the value
38 to be converted to byte-
39 array type. For Tcl_Get‐
40 ByteArrayFromObj and
41 Tcl_SetByteArrayLength,
42 this points to the value
43 from which to get the
44 byte-array value; if
45 objPtr does not already
46 point to a byte-array
47 value, it will be con‐
48 verted to one.
49 int *lengthPtr (out) If non-NULL, filled with
51 the length of the array of
52 bytes in the value.
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54
57 These procedures are used to create, modify, and read Tcl byte-array
58 values from C code. Byte-array values are typically used to hold the
59 results of binary IO operations or data structures created with the
60 binary command. In Tcl, an array of bytes is not equivalent to a
61 string. Conceptually, a string is an array of Unicode characters,
62 while a byte-array is an array of 8-bit quantities with no implicit
63 meaning. Accessor functions are provided to get the string representa‐
64 tion of a byte-array or to convert an arbitrary value to a byte-array.
65 Obtaining the string representation of a byte-array value (by calling
66 Tcl_GetStringFromObj) produces a properly formed UTF-8 sequence with a
67 one-to-one mapping between the bytes in the internal representation and
68 the UTF-8 characters in the string representation.
69 Tcl_NewByteArrayObj and Tcl_SetByteArrayObj will create a new value of
71 byte-array type or modify an existing value to have a byte-array type.
72 Both of these procedures set the value's type to be byte-array and set
73 the value's internal representation to a copy of the array of bytes
74 given by bytes. Tcl_NewByteArrayObj returns a pointer to a newly allo‐
75 cated value with a reference count of zero. Tcl_SetByteArrayObj inval‐
76 idates any old string representation and, if the value is not already a
77 byte-array value, frees any old internal representation. If bytes is
78 NULL then the new byte array contains arbitrary values.
79 Tcl_GetByteArrayFromObj converts a Tcl value to byte-array type and
81 returns a pointer to the value's new internal representation as an
82 array of bytes. The length of this array is stored in lengthPtr if
83 lengthPtr is non-NULL. The storage for the array of bytes is owned by
84 the value and should not be freed. The contents of the array may be
85 modified by the caller only if the value is not shared and the caller
86 invalidates the string representation.
87 Tcl_SetByteArrayLength converts the Tcl value to byte-array type and
89 changes the length of the value's internal representation as an array
90 of bytes. If length is greater than the space currently allocated for
91 the array, the array is reallocated to the new length; the newly allo‐
92 cated bytes at the end of the array have arbitrary values. If length
93 is less than the space currently allocated for the array, the length of
94 array is reduced to the new length. The return value is a pointer to
95 the value's new array of bytes.
96
99 Tcl_GetStringFromObj, Tcl_NewObj, Tcl_IncrRefCount, Tcl_DecrRefCount
100
103 value, binary data, byte array, utf, unicode, internationalization
104Tcl 8.1 Tcl_ByteArrayObj(3)