Tk_GetUid(3) Tk Library Procedures Tk_GetUid(3)

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NAME

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.
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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

Tk Tk_GetUid(3)