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cpointersdeclarationcommand-line-argumentsspiral

Using spiral rule in command line argument

what is the difference between the below declarations?

char *argv[];

and

char *(argv[]);

I think it is same according to spiral rule.

Solution

  • As written, the parentheses make no difference.

    The so-called spiral rule falls out of this simple fact of C grammar: postfix operators such as () and [] have higher precedence than unary operators like *, so expressions like *f() and *a[] are parsed as *(f()) and *(a[]).

    So given a relatively complex expression like

    *(*(*foo)())[N]

    it parses as

         foo            -- foo
   (*foo)           -- is a pointer (parens force grouping)
   (*foo)()         -- to a function
 (*(*foo)())        -- returning a pointer (parens force grouping again)
 (*(*foo)())[N]     -- to an array
*(*(*foo)())[N]     -- of pointer