The "C" standard says that a standalone function name (without trailing
parens) 'degenerates' to the address of the function.

So,

myFooPtr = foo;

and

myFooPtr = &foo;

do the same thing in ANSI C.

Bob Ammerman
RAm Systems

----- Original Message -----
From: "Ricky Hussmann" <gargoyle@IOLINC.NET>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Wednesday, December 11, 2002 1:41 AM
Subject: Re: function pointer syntax in C/C++


> ----- Original Message -----
> From: "Ashley Roll" <ash@DIGITALNEMESIS.COM>
> To: <PICLIST@MITVMA.MIT.EDU>
> Sent: Wednesday, December 11, 2002 1:18 AM
> Subject: Re: function pointer syntax in C/C++
>
>
> > Hi Brendan
> >
> > The "nicest" way is to use typedefs:
> >
> > int foo(int bar);       // function to point to0
> >
> > typedef int (* MyFuncPtrType)(int /* parameters here */);
> >
> > Then you can say:
> >
> > MyFuncPtrType pFunc = &foo;
>
> I'm not quite sure this is right. As far as I know, you don't need the "&"
> before the function name. It may still work, I haven't tried it.
>
> I'm basically adapting the following from my C reference manual:
>
> /* This is the function prototype */
> int foo(int);
>
> /* This is will be the pointer to our function above, called p */
> int (*p) (int);
>
> /* This is a variable to hold the return value of the function */
> int answer;
>
> /* This will assign the address of the function foo to p */
> /* The function name itself is actually a pointer to the function */
> p = foo;
>
> /* Now using the function pointer we can call the function foo */
> answer = (*p) (4);
>
> Look at the above function pointer declaration, the first word is "int".
> This is the return type of your function. Next is (*p). This is the name
of
> the variable, you can call it whatever you want. We could have said int
> (*foo_p) (int) if we wanted, its just the variable name.
>
> The final part are the parameters of the function. Say we had another
> function we wanted to make a pointer to called foo2, and say it looked
like:
>
>     int foo2(int, int, float);
>
> Then the declaration of the pointer variable would look like this:
>
>     int (*foo2_p) (int, int, float);
>
> We would then assign the pointer like this:
>
>     foo2_p = foo2;
>
> And we could call the function like this:
>
>     answer = (*foo2_p) (1, 2, 3.0);
>
> Again, foo2_p is just the name of the variable, but you can call it
whatever
> you want. This is the way defined by the ANSI C standard, and is
guaranteed
> to work. Ash's answer may still be correct, I didn't check.
>
> I really hope this helps. Good luck in your coding.
>
> Ricky Hussmann
>
> > > -----Original Message-----
> > > From: pic microcontroller discussion list
> > > [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Brendan Moran
> > > Sent: Wednesday, 11 December 2002 3:41 PM
> > > To: PICLIST@MITVMA.MIT.EDU
> > > Subject: function pointer syntax in C/C++
> > >
> > >
> > > On most C syntax I do just fine, but function pointers are always a
> > > head-scratcher for me.
> > >
> > > If I wanted to declare a pointer to this function:
> > >
> > > int foo(int bar);
> >
> > --
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> >
> >
> >
> >
>
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>

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