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Re: Strange C behaviour

On Tue, 4 Apr 2000 14:54:29 +0200, Michael Meskes <meskes@debian.org> said:
> When I started learning C (okay, that's quite some 15 years ago) I think I
> learned that an array is the same as a pointer. So I'd expect it to be
> pointer to the pointer.

If there are things that will slip even the eyes of the most
experienced C programmer, it is type promotion.

<book title="KnR, 1st ed.," citationfrom="Expert C Programming">
Every char in an expression is converted to an int .... Notice that
all the float's in an expression are converted to double....Since a
function argument is an expression, type conversions also take place
when arguments are passed to functions: in particular, char an dshort
become int, float becomes double.

<Book title="Expert C Programming[1]">
Original Type           Usually promoted to
char                    int
bit-field               int
enum                    int
unsigned char           int
short                   int
unsigned short          int
float                   double
array of /anything/     pointer to /anything/

So, you see: arrays _are_ pointers of a kind, just because an array
is converted to a (constant) pointer when used in an
expression. Therefore you can also use pointer[3] and array[3] in an
expression and the compiler does not even need special rules to tell
the difference, because it only needs the rule to access
*(pointer+3). (-8

> Michael

apologies to Peter van der Linden and
kind regards,

[1]     Title=Expert C Programming
        subtitle=Deep C Secrets
        Author=Peter van der Linden
        Publisher=Prentice Hall/SunSoft Press
(I can only recommend every C Programmer to read this book. It is
amusing and very interesting to read)
Andreas Stefan Fuchs                             in Real Life aka
asf@acm.org, asfuchs@gmx.at, asf@ycom.at         in NNTP and SMTP,
antifuchs                                        in IRCNet and
Relf Herbstfresser, Male 1/2 Elf Priest          in AD&D

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