From: flupke <schawat AT club-internet DOT fr>
Newsgroups: comp.os.msdos.djgpp
Subject: Function pointers in C++
Date: Tue, 31 Aug 1999 13:36:51 +0200
Organization: Club-Internet (France)
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

Hello.

I don't know if i'm doing a "c++ misunderstanding" or if it's a djgpp
problem, but here is my problem anyway.
When i execute this piece of code:

***********************
#include <iostream.h>

class glou
{
public:
    int c;

    glou()
    {
        c = 0;
        a = &b;
    }

    void (*a)();

    void b()
    {
        c++;
    }
};

int main()
{
    glou blou;

    cout << blou.c << endl;

    blou.a();
    cout << blou.c << endl;

    blou.b();
    cout << blou.c << endl;

    return 0;
}

***********************

I get the output:
0
0
1

Also, i get a warning for the second line of the constructor:
tst.cc(11) Warning:  converting from `void (glou::*)()' to `void (*)()'


So i have two questions:
-- how to declare my function pointer so that i get no warning ? If i
try to change "void (*a)()" to: "void (glou::*a)()", i get this error:
tst.cc(28) Error: no match for call to `(void (glou::*)()) ()'
   and "void (*glou::a)()" gives me the same warning and output as "void
(*a)()"...

-- how does c++ handle function calling ? why doesn't a() increment
blou::c ?


Thanks for reading this loooong message ;)


Whooops, i just tried to compile the source for the 1000'th time and now
i get:
tst.cc(28) Error: Internal compiler error.
tst.cc(28) Error: Please submit a full bug report to
`bug-g++@prep.ai.mit.edu

(with the "void (glou::*a)()" version of the declaration)

... if i compile it again, it randomly gives me a "compiler" or "no
match for call" error. Please tell me if i'm doing crappy c++ or if it's
really a bug (i use gcc 2.8.0, and rhide under windoze).