Tk_GetUid, Tk_Uid - convert from string to unique identifier
- char *string (in)
- String for which the corresponding unique 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