NAME

       Tk_GetUid,  Tk_Uid - convert from string to unique identi­
       fier


SYNOPSIS

       #include <tk.h>

       #typedef char *Tk_Uid

       Tk_Uid
       Tk_GetUid(string)


ARGUMENTS

       char         *string            (in)      String for which
                                                 the  correspond­
                                                 ing unique iden­
                                                 tifier        is
                                                 desired.
_________________________________________________________________



DESCRIPTION

       Tk_GetUid returns the unique identifier  corresponding  to
       string.   Unique identifiers are similar to atoms in Lisp,
       and are used in Tk to speed up comparisons  and  searches.
       A  unique identifier (type Tk_Uid) is a string pointer and
       may be used anywhere that a variable of  type  ``char  *''
       could be used.  However, there is guaranteed to be exactly
       one unique identifier for  any  given  string  value.   If
       Tk_GetUid  is  called  twice,  once with string a and once
       with string b, and if a and b have the same  string  value
       (strcmp(a,  b)  ==  0), then Tk_GetUid will return exactly
       the same Tk_Uid  value  for  each  call  (Tk_GetUid(a)  ==
       Tk_GetUid(b)).   This  means that variables of type Tk_Uid
       may be compared directly (x == y) without having  to  call
       strcmp.  In addition, the return value from Tk_GetUid will
       have  the  same  string  value  as  its   argument   (str­
       cmp(Tk_GetUid(a), a) == 0).



KEYWORDS

       atom, unique identifier