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

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

40       atom, unique identifier
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44Tk                                                                Tk_GetUid(3)