----- Original Message ----- 
From: "Gerhard Fiedler" <lists@connectionbrazil.com>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Tuesday, June 02, 2009 2:21 PM
Subject: Re: [PIC] MPLAB SIM PROBLEM - help


> Olin Lathrop wrote:
>
>> Isaac Marino Bavaresco wrote:
>>> Many don't know, but "x = 1[p];" is valid and is the same as
>>> "x=p[1];".
>>
>> I find that hard to believe.  What data type would 1[p] have?  How
>> would it know the size of each element?  Can you show complete
>> example code that actually compiles using this construct?
>
> Both arrays need a declaration that defines their member type.
>
> 1[p] could point to (1 + p * sizeof(memberType)). (Not sure this is
> legal, but it could be -- given an implicit conversion from int to an
> array address.)
>
> p[1] would point to (p + 1 * sizeof(memberType)).
>
> If you declare the arrays so that sizeof(memberType)==1, this could
> work.
>
> I don't see any use for this "trick", though...
>
> Gerhard

Not true. As I mentioned before

a[b] === b[a] === *(a+b) === *(b+a)

This means that as long as one of a and b is a pointer (or array name) and 
the other an integer type then the syntax is perfectly valid "C". There are 
no restrictions on the type pointed to.

-- Bob Ammerman
RAm Systems

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