Is main() a callback function?

[Stefan_Lang]

Only if used as such, e. g. in this code:

#include

using namespace std;

static int call_countdown = 3;
typedef int (*MyCallbackFun)();
int foo(MyCallbackFun cb, int count)
{
static int foo_counter = 0;
++foo_counter;
cout << "enter foo[" << foo_counter <<"]: " << count << endl;
int result = cb();
cout << "exit foo[" << foo_counter << "]: " << result << endl;
return result;
}
int bar()
{
static int bar_counter = 0;
++bar_counter;
cout << "bar[" << bar_counter << "]" << endl;
return -1;
}
int main()
{
static int call_counter = 0;
++call_counter;
cout << "enter main[" << call_counter << "]" << endl;

int result = 0;
if (call\_counter < 5)
{
    result = (call\_counter>2)
        ? foo(bar, call\_counter)
        : foo(main, call\_counter);
}
cout << "exit main\[" << call\_counter << "\]: " << result << endl;

return call\_counter;

}

You can test it here: https://www.onlinegdb.com/online_c++_compiler[^] or trust me that the output is:

enter main[1]
enter foo[1]: 1
enter main[2]
enter foo[2]: 2
enter main[3]
enter foo[3]: 3
bar[1]
exit foo[3]: -1
exit main[3]: -1
exit foo[3]: 3
exit main[3]: 3
exit foo[3]: 3
exit main[3]: 3

The tricky bit about this is that by using main() as a callback function, you're also using it recursively, which complicates matters considerably: it's easy to mess up the code and get an endless recursion. (that's why I added counters and output in every function) It's doable, but definitiely not a good idea.

GOTOs are a bit like wire coat hangers: they tend to breed in the darkness, such that where there once were few, eventually there are many, and the program's architecture collapses beneath them. (Fran Poretto)

[TheGreatAndPowerfulOz]

lol, you got me there.

#SupportHeForShe Government can give you nothing but what it takes from somebody else. A government big enough to give you everything you want is big enough to take everything you've got, including your freedom.-Ezra Taft Benson You must accept 1 of 2 basic premises: Either we are alone in the universe or we are not alone. Either way, the implications are staggering!-Wernher von Braun

[Rick York]

There were only minor changes. For the most part, what you wrote is correct.

"They have a consciousness, they have a life, they have a soul! Damn you! Let the rabbits wear glasses! Save our brothers! Can I get an amen?"

[Slow Eddie]

No. It's a state in the Northeast. :laugh:

Oh Well.....