tcldoc Tcl/Tk 9.0.4
/

Home › Tk Library Procedures Tk

Tk_GetUid C API

Convert from string to unique identifier

Also documents Tk_Uid

literal type exactly as shown argument replace with your value ?optional? may be omitted

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

Copyright#