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  3. Is main() a callback function?

Is main() a callback function?

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  • D DRHuff

    Well it never called me back - and I thought we had such a connection... :(( :(( :mad: :(( :((

    I, for one, like Roman Numerals.

    T Offline
    T Offline
    TheGreatAndPowerfulOz
    wrote on last edited by
    #35

    Did you give it your number, baby? ;P

    #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

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    • H honey the codewitch

      Focused using butterflies

      Real programmers use butterflies

      T Offline
      T Offline
      TheGreatAndPowerfulOz
      wrote on last edited by
      #36

      honey the codewitch wrote:

      Focused using butterflies

      that are manipulated using gravitic lenses

      #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

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      • T TheGreatAndPowerfulOz

        honey the codewitch wrote:

        Focused using butterflies

        that are manipulated using gravitic lenses

        #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

        H Offline
        H Offline
        honey the codewitch
        wrote on last edited by
        #37

        created from the silk of butterfly cocoons :-D

        Real programmers use butterflies

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        • OriginalGriffO OriginalGriff

          Difficult to tell, it was yelling a lot and slurring it's words.

          "I have no idea what I did, but I'm taking full credit for it." - ThisOldTony AntiTwitter: @DalekDave is now a follower!

          D Offline
          D Offline
          DRHuff
          wrote on last edited by
          #38

          So it was yaccing with a lisp?

          I, for one, like Roman Numerals.

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          • R Rob Philpott

            That reminds me of a thing I read some time back, titled something along the lines of 'the 50 things Windows does before hitting main()'. Can't find it but it's out there somewhere, by one of the SysInternals lot I think. It was both interesting and really boring at the same time.

            Regards, Rob Philpott.

            R Offline
            R Offline
            Rick York
            wrote on last edited by
            #39

            If you have Visual Studio you can see what the C run-time library does by looking at its source. I was checking that out just today.

            "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?"

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            • R Rick York

              Actually things are a little different. In the Visual Studio source, VC/Tools/MSVC/**version**/crt/src/vcruntime/vcstartup_internal.h has the prototypes and the calls are in exe_common.inl. WinMain and main are two different calls along with their wide character versions.

              "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?"

              L Offline
              L Offline
              Lost User
              wrote on last edited by
              #40

              I suspected this might be the case, but I have not had access to the source for a number of years.

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              • R Rob Philpott

                I can't make up my mind.

                Regards, Rob Philpott.

                S Offline
                S Offline
                Stefan_Lang
                wrote on last edited by
                #41

                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)

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                • H honey the codewitch

                  created from the silk of butterfly cocoons :-D

                  Real programmers use butterflies

                  T Offline
                  T Offline
                  TheGreatAndPowerfulOz
                  wrote on last edited by
                  #42

                  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

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                  • L Lost User

                    I suspected this might be the case, but I have not had access to the source for a number of years.

                    R Offline
                    R Offline
                    Rick York
                    wrote on last edited by
                    #43

                    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?"

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                    • R Rob Philpott

                      I can't make up my mind.

                      Regards, Rob Philpott.

                      S Offline
                      S Offline
                      Slow Eddie
                      wrote on last edited by
                      #44

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

                      Oh Well.....

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