'\" '\" Copyright (c) 1997 Sun Microsystems, Inc. '\" '\" See the file "license.terms" for information on usage and redistribution '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. '\" '\" RCS: @(#) GetIndex.3,v 1.5 2003/01/21 19:39:59 hunt Exp '\" .so man.macros .TH Tcl_GetIndexFromObj 3 8.1 Tcl "Tcl Library Procedures" .BS .SH NAME Tcl_GetIndexFromObj, Tcl_GetIndexFromObjStruct \- lookup string in table of keywords .SH SYNOPSIS .nf \fB#include <tcl.h>\fR .sp int \fBTcl_GetIndexFromObj\fR(\fIinterp, objPtr, tablePtr, msg, flags, indexPtr\fR) .VS .sp int \fBTcl_GetIndexFromObjStruct\fR(\fIinterp, objPtr, structTablePtr, offset, msg, flags, indexPtr\fR) .VE .SH ARGUMENTS .AS "CONST char" **tablePtr .AP Tcl_Interp *interp in Interpreter to use for error reporting; if NULL, then no message is provided on errors. .AP Tcl_Obj *objPtr in/out The string value of this object is used to search through \fItablePtr\fR. The internal representation is modified to hold the index of the matching table entry. .AP "CONST char" **tablePtr in An array of null-terminated ASCII strings. The end of the array is marked by a NULL string pointer. .AP "CONST VOID" *structTablePtr in An array of arbitrary type, typically some \fBstruct\fP type. The first member of the structure must be a null-terminated ASCII string. The size of the structure is given by \fIoffset\fP. .VS .AP int offset in The offset to add to structTablePtr to get to the next entry. The end of the array is marked by a NULL string pointer. .VE .AP "CONST char" *msg in Null-terminated string describing what is being looked up, such as \fBoption\fR. This string is included in error messages. .AP int flags in OR-ed combination of bits providing additional information for operation. The only bit that is currently defined is \fBTCL_EXACT\fR. .AP int *indexPtr out The index of the string in \fItablePtr\fR that matches the value of \fIobjPtr\fR is returned here. .BE .SH DESCRIPTION .PP This procedure provides an efficient way for looking up keywords, switch names, option names, and similar things where the value of an object must be one of a predefined set of values. \fIObjPtr\fR is compared against each of the strings in \fItablePtr\fR to find a match. A match occurs if \fIobjPtr\fR's string value is identical to one of the strings in \fItablePtr\fR, or if it is a unique abbreviation for exactly one of the strings in \fItablePtr\fR and the \fBTCL_EXACT\fR flag was not specified; in either case the index of the matching entry is stored at \fI*indexPtr\fR and TCL_OK is returned. .PP If there is no matching entry, TCL_ERROR is returned and an error message is left in \fIinterp\fR's result if \fIinterp\fR isn't NULL. \fIMsg\fR is included in the error message to indicate what was being looked up. For example, if \fImsg\fR is \fBoption\fR the error message will have a form like \fBbad option "firt": must be first, second, or third\fR. .PP If \fBTcl_GetIndexFromObj\fR completes successfully it modifies the internal representation of \fIobjPtr\fR to hold the address of the table and the index of the matching entry. If \fBTcl_GetIndexFromObj\fR is invoked again with the same \fIobjPtr\fR and \fItablePtr\fR arguments (e.g. during a reinvocation of a Tcl command), it returns the matching index immediately without having to redo the lookup operation. Note: \fBTcl_GetIndexFromObj\fR assumes that the entries in \fItablePtr\fR are static: they must not change between invocations. If the value of \fIobjPtr\fR is the empty string, \fBTcl_GetIndexFromObj\fR will treat it as a non-matching value and return TCL_ERROR. .VS .PP \fBTcl_GetIndexFromObjStruct\fR works just like \fBTcl_GetIndexFromObj\fR, except that instead of treating \fItablePtr\fR as an array of string pointers, it treats it as the first in a series of string ptrs that are spaced apart by \fIoffset\fR bytes. This is particularly useful when processing things like \fBTk_ConfigurationSpec\fR, whose string keys are in the same place in each of several array elements. .VE .SH "SEE ALSO" Tcl_WrongNumArgs .SH KEYWORDS index, object, table lookup