1Tk_GetUid(3)                 Tk Library Procedures                Tk_GetUid(3)
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NAME

8       Tk_GetUid, Tk_Uid - convert from string to unique identifier
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SYNOPSIS

11       #include <tk.h>
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13       Tk_Uid
14       Tk_GetUid(string)
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ARGUMENTS

17       char *string (in)                         String  for  which the corre‐
18                                                 sponding unique identifier is
19                                                 desired.
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DESCRIPTION

23       Tk_GetUid  returns  the  unique  identifier  corresponding  to  string.
24       Unique identifiers are similar to atoms in Lisp, and are used in Tk  to
25       speed  up  comparisons and searches.  A unique identifier (type Tk_Uid)
26       is a string pointer and may be used anywhere that a  variable  of  type
27       “char *” could be used.  However, there is guaranteed to be exactly one
28       unique identifier for any given string value.  If Tk_GetUid  is  called
29       twice,  once  with string a and once with string b, and if a and b have
30       the same string value (strcmp(a, b) == 0), then Tk_GetUid  will  return
31       exactly   the   same  Tk_Uid  value  for  each  call  (Tk_GetUid(a)  ==
32       Tk_GetUid(b)).  This means that variables of type Tk_Uid  may  be  com‐
33       pared  directly  (x  == y) without having to call strcmp.  In addition,
34       the return value from Tk_GetUid will have the same string value as  its
35       argument (strcmp(Tk_GetUid(a), a) == 0).
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KEYWORDS

38       atom, unique identifier
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42Tk                                                                Tk_GetUid(3)