getuid(3Tk)

NAME
     Tk_GetUid, Tk_Uid - convert from string to unique identifier

SYNOPSIS
     #include <tk.h>

     #typedef char *Tk_Uid

     Tk_Uid
     Tk_GetUid(string)

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


KEYWORDS
     atom, unique identifier