• imr1984 (5/5) Feb 06 2004 why is it that when you want to assign a function pointer to a function,...
• Manfred Nowak (6/8) Feb 06 2004 Have you read http://www.digitalmars.com/d/property.html, [cited 06.02.0...
• Andy Friesen (4/10) Feb 06 2004 The rule is really simple in D: You *always* need the ampersand when
• Ilya Minkov (23/28) Feb 06 2004 Don't gesitate to put an ampersand (&) in C. It works just as well. I
• Sean Kelly (7/12) Feb 07 2004 In C/C++ the address-of operator is implied for C-style functions so use...
• Walter (8/13) Feb 07 2004 you

imr1984 <imr1984_member pathlink.com> writes:

why is it that when you want to assign a function pointer to a function, you
have to use the address of operator ( & ) unlike in C/C++. This kinda annoys me
because im at university where they force me to use C, and im always having to
think to myself "should i put an ampersand here or not?". At the very least make
it optional.

Manfred Nowak <svv1999 hotmail.com> writes:

On Fri, 06 Feb 2004 13:12:00 +0000, imr1984 wrote:

 why is it that when you want to assign a function pointer to a function, you
 have to use the address of operator ( & ) unlike in C/C++.

Have you read http://www.digitalmars.com/d/property.html, [cited 06.02.04]
about functions as properties?

And, I think I do not grep you fully: do you really mean assigning a
function pointer to a function, or the other way round?

So long.

Andy Friesen <andy ikagames.com> writes:

imr1984 wrote:

 why is it that when you want to assign a function pointer to a function, you
 have to use the address of operator ( & ) unlike in C/C++. This kinda annoys me
 because im at university where they force me to use C, and im always having to
 think to myself "should i put an ampersand here or not?". At the very least
make
 it optional.
 

The rule is really simple in D: You *always* need the ampersand when 
taking the address of something.

  -- andy

Ilya Minkov <minkov cs.tum.edu> writes:

imr1984 wrote:
 why is it that when you want to assign a function pointer to a function, you
 have to use the address of operator ( & ) unlike in C/C++. This kinda annoys me
 because im at university where they force me to use C, and im always having to
 think to myself "should i put an ampersand here or not?". At the very least
make
 it optional.

Don't gesitate to put an ampersand (&) in C. It works just as well. I 
find that it's a point of inconsistency in C that you can use both 
adress-of and a function name itself as if it was the same. If you put & 
in C you don't get adress-of-adress, it's simply the same as without in 
context of function pointers. You have to put yet another & to get 
adress-of-adress IIRC. (btw, don't do this adress of pointer trick 
unless you know where this adress is stored! or don't do it at all!). 
Finally, both C++ and D have a more elegant replacement to function 
pointers, which is virtual methods of classes.

In C i got caught a few times. I forgot to put () after a function call 
without parameters. And since this yuilds a function adress, which is a 
value, which is discarded since nothing sensible is done with it, the 
function doesn't get called. Nothing happens. The program just runs 
further. I tried to trace into the function with a debugger for hours, 
till i finally saw that i left out ()! :> So i guess it would be good 
that it stays an error to assign a function to function pointer.

It happened a few times while writing my first C prog - i was a more or 
less experienced Delphi developer back then and was really frustrated by 
endless bugs caused by C - and then when using BCX which generated wrong 
code of this sort under some circumstance.

-eye

PS. tomorrow i have an exam - wish me luck

Sean Kelly <sean ffwd.cx> writes:

imr1984 wrote:

 why is it that when you want to assign a function pointer to a function, you
 have to use the address of operator ( & ) unlike in C/C++. This kinda annoys me
 because im at university where they force me to use C, and im always having to
 think to myself "should i put an ampersand here or not?". At the very least
make
 it optional.

In C/C++ the address-of operator is implied for C-style functions so use 
of it is optional.  It's not implied for member function pointers so use 
there is mandatory AFAIK.  I like that in D they enforce a degree of 
consistency here.  But that also means you're free to always use the '&' 
in C as well.


Sean

"Walter" <walter digitalmars.com> writes:

"imr1984" <imr1984_member pathlink.com> wrote in message
news:c003r0$l5v$1 digitaldaemon.com...
 why is it that when you want to assign a function pointer to a function,

you
 have to use the address of operator ( & ) unlike in C/C++. This kinda

annoys me
 because im at university where they force me to use C, and im always

having to
 think to myself "should i put an ampersand here or not?". At the very

least make
 it optional.

It's mandatory in D to eliminate parsing ambiguities with respect to
properties.