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.
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
