1Tcl_GetIndexFromObj(3) Tcl Library Procedures Tcl_GetIndexFromObj(3)
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6
8 Tcl_GetIndexFromObj, Tcl_GetIndexFromObjStruct - lookup string in table
9 of keywords
10
12 #include <tcl.h>
13 int
15 Tcl_GetIndexFromObj(interp, objPtr, tablePtr, msg, flags,
16 indexPtr)
17 int │
19 Tcl_GetIndexFromObjStruct(interp, objPtr, structTablePtr, offset, │
20 msg, flags, indexPtr) │
21
23 Tcl_Interp *interp (in) Interpreter to use for error
24 reporting; if NULL, then no message
25 is provided on errors.
26 Tcl_Obj *objPtr (in/out) The string value of this object is
28 used to search through tablePtr.
29 The internal representation is mod‐
30 ified to hold the index of the
31 matching table entry.
32 CONST char **tablePtr (in) An array of null-terminated
34 strings. The end of the array is
35 marked by a NULL string pointer.
36 CONST VOID *structTablePtr(in) An array of arbitrary type, typi‐
38 cally some struct type. The first
39 member of the structure must be a
40 null-terminated string. The size
41 of the structure is given by off‐
42 set. │
43 int offset (in) │
45 The offset to add to structTablePtr │
46 to get to the next entry. The end │
47 of the array is marked by a NULL │
48 string pointer.
49 CONST char *msg (in) Null-terminated string describing
51 what is being looked up, such as
52 option. This string is included in
53 error messages.
54 int flags (in) OR-ed combination of bits providing
56 additional information for opera‐
57 tion. The only bit that is cur‐
58 rently defined is TCL_EXACT.
59 int *indexPtr (out) The index of the string in tablePtr
61 that matches the value of objPtr is
62 returned here.
63_________________________________________________________________
64
67 This procedure provides an efficient way for looking up keywords,
68 switch names, option names, and similar things where the value of an
69 object must be one of a predefined set of values. ObjPtr is compared
70 against each of the strings in tablePtr to find a match. A match
71 occurs if objPtr's string value is identical to one of the strings in
72 tablePtr, or if it is a non-empty unique abbreviation for exactly one
73 of the strings in tablePtr and the TCL_EXACT flag was not specified; in
74 either case the index of the matching entry is stored at *indexPtr and
75 TCL_OK is returned.
76 If there is no matching entry, TCL_ERROR is returned and an error mes‐
78 sage is left in interp's result if interp isn't NULL. Msg is included
79 in the error message to indicate what was being looked up. For exam‐
80 ple, if msg is option the error message will have a form like bad
81 option "firt": must be first, second, or third.
82 If Tcl_GetIndexFromObj completes successfully it modifies the internal
84 representation of objPtr to hold the address of the table and the index
85 of the matching entry. If Tcl_GetIndexFromObj is invoked again with
86 the same objPtr and tablePtr arguments (e.g. during a reinvocation of a
87 Tcl command), it returns the matching index immediately without having
88 to redo the lookup operation. Note: Tcl_GetIndexFromObj assumes that
89 the entries in tablePtr are static: they must not change between invo‐
90 cations. If the value of objPtr is the empty string, Tcl_GetIndexFro‐
91 mObj will treat it as a non-matching value and return TCL_ERROR. │
92 Tcl_GetIndexFromObjStruct works just like Tcl_GetIndexFromObj, except │
94 that instead of treating tablePtr as an array of string pointers, it │
95 treats it as the first in a series of string ptrs that are spaced apart │
96 by offset bytes. This is particularly useful when processing things │
97 like Tk_ConfigurationSpec, whose string keys are in the same place in │
98 each of several array elements.
99
102 Tcl_WrongNumArgs
103
106 index, object, table lookup
107Tcl 8.1 Tcl_GetIndexFromObj(3)