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Re: [OT] A bit confused on pointers...
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Re: [OT] A bit confused on pointers...


  • Subject: Re: [OT] A bit confused on pointers...
  • From: Alastair Houghton <email@hidden>
  • Date: Fri, 30 Dec 2005 15:14:47 +0000

On 30 Dec 2005, at 14:01, Steve Bird wrote:

On Dec 30, 2005, at 5:10 AM, Andreas Mayer wrote:
it's customary to write int *ptr instead of int* ptr, which would be more accurate in my opinion. The '*' modifies the type, after all, not the identifier.

Coming from Pascal (where you are forced to write var p: ^integer), this made perfect sense to me, UNTIL I discovered that it doesn't work the way I thought it would.

In Pascal, var p1,p2: ^integer declares TWO pointers to integers, but in C, int* p1, p2 does NOT. As much as it makes sense to read it that way, the compiler sees it otherwise.

The way C interprets it makes perfect sense also; '*' is a unary right-associative operator, wherever it appears in the code. Same for '&' in C++. i.e. if you write "int* a" (or in C++ "int& a"), you are deluding yourself... the compiler will never read things that way around, no matter how much whitespace you insert.

Anyway, I think this has probably been done to death now, and since it's really basic C stuff, it'd be a good idea for anyone who is still confused to find themselves a good book on C. I recommend avoiding the plethora of brightly-coloured books on C++ and just finding something that concentrates on C; the C++ books often spend a lot of time on the new features of C++ at the expense of more coverage of the basics of the underlying C language.

The FAQ document I wrote some time ago lists a few books that have been recommended in the past; see <http://www.alastairs-place.net/ cocoa/faq.txt>. It needs a bit of updating (perhaps I'll get some time to do this soon... we'll see).

More experienced programmers might like to get a copy of the ANSI C spec itself (Wiley do a nice printed version, ISBN 0-470-84573-2; the C++ spec. is also available under ISBN 0-470-84674-7).

Kind regards,

Alastair.

--
http://www.alastairs-place.net

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    • Re: [OT] A bit confused on pointers...
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References: 
 >[OT] A bit confused on pointers... (From: Sanri Parov <email@hidden>)
 >Re: [OT] A bit confused on pointers... (From: Camillo Lugaresi <email@hidden>)
 >Re: [OT] A bit confused on pointers... (From: Andreas Mayer <email@hidden>)
 >Re: [OT] A bit confused on pointers... (From: Clark Cox <email@hidden>)
 >Re: [OT] A bit confused on pointers... (From: Andreas Mayer <email@hidden>)
 >Re: [OT] A bit confused on pointers... (From: Steve Bird <email@hidden>)

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