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GetUid.3tk

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NAME

Tk_GetUid, Tk_Uid - convert from string to unique identifier

SYNOPSIS

 #include <tk.h>
 
 #typedef char *Tk_Uid
 
 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