Skribent: karl Dato: Til: dng Emne: Re: [DNG] Making sense of C pointer syntax.
Edward Bartolo:
... > However, C pointer syntax is proving to be as unintuitive as it can
> be. ... > I want to understand, as opposed to knowing by rote, the
> mechanism why they work. ...
///
I think one source of confusion re. c-pointers is that they are
declared "as they are used", but you migth not use them like that.
If you take
int *ix;
then *ix will be an int, and you can _deduce_ that ix is a pointer to
an int, but you don't say that directly. In your code you try to avoid
the issue by writing "int* i;" and treating "int*" to be a "pointer"
declaration. But "int * i ;" is four tokens regardless how you write it,
you could just as well have written it as "int*i;" or "int *i;", same thing.
To exemplify the "as they are used" statement, take a function pointer
declaration:
here you cannot conveniently move the "*" to the "void" so it will look
like a "pointer" declaration; it declares log_func to be something which
if used as (*log_func)(a, b, d) will "give" you a void value.
///
There is also a visual mismatch in c with a declaration of a pointer
with an initializer. Example:
int *ix = (int *) malloc(sizeof(int));
This line is the same thing as
int *ix; /* i.e. *ix is an int */
ix = (int *) malloc(sizeof(int)); /* look no "*" */
So, int *ix = value; says two things;
a: it declares an "ix" such as when ix is used as "*ix" it will be an int
b: ix = value