Tk_GetUid(3)

Tk_GetUid(3)          Tk Library Procedures          Tk_GetUid(3)

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NAME

     Tk_GetUid, Tk_Uid - convert from string to unique identifier

SYNOPSIS

     #include <tk.h>

     Tk_Uid
     Tk_GetUid(string)

ARGUMENTS

     char *string (in)                         String  for  which
                                               the  corresponding
                                               unique  identifier
                                               is desired.
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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 (strcmp(Tk_GetUid(a), a) == 0).

KEYWORDS

     atom, unique identifier

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