Marcin Kasprzak <no@[EMAIL PROTECTED]
> writes:
> Silly question - what is the most elegant way of compiling a code
similar
> to this one?
> [code for mutually referential structures]
Refer to the C FAQ.
1.14: I can't seem to define a linked list successfully. I tried
typedef struct {
char *item;
NODEPTR next;
} *NODEPTR;
but the compiler gave me error messages. Can't a structure in C
contain a pointer to itself?
A: Structures in C can certainly contain pointers to themselves;
the discussion and example in section 6.5 of K&R make this
clear. The problem with the NODEPTR example is that the typedef
has not been defined at the point where the "next" field is
declared. To fix this code, first give the structure a tag
("struct node"). Then, declare the "next" field as a simple
"struct node *", or disentangle the typedef declaration from the
structure definition, or both. One corrected version would be
struct node {
char *item;
struct node *next;
};
typedef struct node *NODEPTR;
and there are at least three other equivalently correct ways of
arranging it.
A similar problem, with a similar solution, can arise when
attempting to declare a pair of typedef'ed mutually referential
structures.
See also question 2.1.
References: K&R1 Sec. 6.5 p. 101; K&R2 Sec. 6.5 p. 139; ISO
Sec. 6.5.2, Sec. 6.5.2.3; H&S Sec. 5.6.1 pp. 132-3.
--
"I've been on the wagon now for more than a decade. Not a single goto
in all that time. I just don't need them any more. I don't even use
break or continue now, except on social occasions of course. And I
don't get carried away." --Richard Heathfield
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