Tk_GetUid - Man Page

convert from string to unique identifier


#include <tk.h>



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

Referenced By

The man page Tk_Uid(3) is an alias of Tk_GetUid(3).

Tk Library Procedures