DragonFly On-Line Manual Pages
Tk_GetUid(3) Tk Library Procedures Tk_GetUid(3)
Tk_GetUid, Tk_Uid - convert from string to unique identifier
char *string (in) String for which the
identifier is desired.
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).
atom, unique identifier