'\"'\" Copyright (c) 1990 The Regents of the University of California.'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.'\"'\" See the file "license.terms" for information on usage and redistribution'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.'\" '\" SCCS: @(#) GetUid.3 1.10 96/03/26 18:12:55'\" .so man.macros.TH Tk_GetUid 3 "" Tk "Tk Library Procedures".BS.SH NAMETk_GetUid, Tk_Uid \- convert from string to unique identifier.SH SYNOPSIS.nf\fB#include <tk.h>\fR.sp\fB#typedef char *Tk_Uid\fR.spTk_Uid\fBTk_GetUid\fR(\fIstring\fR).SH ARGUMENTS.AP char *string inString for which the corresponding unique identifier isdesired..BE.SH DESCRIPTION.PP\fBTk_GetUid\fR returns the unique identifier correspondingto \fIstring\fR.Unique identifiers are similar to atoms in Lisp, and are usedin Tk to speed up comparisons andsearches.  A unique identifier (type Tk_Uid) is a string pointerand may be used anywhere that a variable of type ``char *''could be used.  However, there is guaranteed to be exactlyone unique identifier for any given string value.  If \fBTk_GetUid\fRis called twice, once with string \fIa\fR and once with string\fIb\fR, and if \fIa\fR and \fIb\fR have the same string value(strcmp(a, b) == 0), then \fBTk_GetUid\fR will return exactlythe same Tk_Uid value for each call (Tk_GetUid(a) == Tk_GetUid(b)).This means that variables of typeTk_Uid may be compared directly (x == y) without having to call\fBstrcmp\fR.In addition, the return value from \fBTk_GetUid\fR will have thesame string value as its argument (strcmp(Tk_GetUid(a), a) == 0)..SH KEYWORDSatom, unique identifier