Tk_GetUid(3) Tk Library Procedures Tk_GetUid(3) 







Tk_GetUid, Tk_Uid - convert from string to unique identifier








#include <tk.h>

Tk_Uid
Tk_GetUid(string)









  
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







  

    
    Tk