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QOTD

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  • R Ryan Johnston 0

    Wow, interesting... I guess the only difference is one keystroke, but I am just surprised. What kind of programming do you do? Ryan Johnston

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    Chris Losinger
    wrote on last edited by
    #13

    there's probably some deep metaphysical reason why people want to use (*it). instead of it-> . i just do it because that's how i learned it. Ryan Johnston wrote: What kind of programming do you do? a little of everything, but mostly 2d graphics. -c


    Conservative: One who admires radicals centuries after they're dead. -- Leo C. Rosten

    image effects!

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    • D David Stone

      Congrats to Christian Graus for thinking up the QOTD. I believe this is the first one I've seen from a CPian. Of course, I can't answer because I haven't a clue when it comes to STL. So I'll just leave the answering of it to the rest of you. :) David Stone It seemed similar to someone saying, "Would you like to meet my knife collection?" Ryan Johnston on Elaine's sig

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      Nemanja Trifunovic
      wrote on last edited by
      #14

      The answer is C) (*it) is the value, so &(*it) is the address of the value. Or did I miss something? I vote pro drink :beer:

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      • C Chris Losinger

        Ryan Johnston wrote: Are you serious? yes, 100%. -c


        Conservative: One who admires radicals centuries after they're dead. -- Leo C. Rosten

        image effects!

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        David Wulff
        wrote on last edited by
        #15

        :omg:


        David Wulff http://www.davidwulff.co.uk

        One 18yrs male, red and white, good condition; daily servicing required. £500 collect ono.

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        • N Nemanja Trifunovic

          The answer is C) (*it) is the value, so &(*it) is the address of the value. Or did I miss something? I vote pro drink :beer:

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          Shog9 0
          wrote on last edited by
          #16

          Nemanja Trifunovic wrote: Or did I miss something? No, you are correct. Any other way is less safe.

          ---

          Shog9 If I could sleep forever, I could forget about everything...

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          • C Chris Losinger

            there's probably some deep metaphysical reason why people want to use (*it). instead of it-> . i just do it because that's how i learned it. Ryan Johnston wrote: What kind of programming do you do? a little of everything, but mostly 2d graphics. -c


            Conservative: One who admires radicals centuries after they're dead. -- Leo C. Rosten

            image effects!

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            Colin Leitner
            wrote on last edited by
            #17

            Looking into the MSDN can open eyes! iterator overloads operator*. plain and simple. Somehow the STL trys to use references wherever possible.

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            • D David Wulff

              :omg:


              David Wulff http://www.davidwulff.co.uk

              One 18yrs male, red and white, good condition; daily servicing required. £500 collect ono.

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              C Offline
              Chris Losinger
              wrote on last edited by
              #18

              sadly, that used up the last of my "serious" for today. time for beer. -c


              Conservative: One who admires radicals centuries after they're dead. -- Leo C. Rosten

              image effects!

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              • N Nemanja Trifunovic

                The answer is C) (*it) is the value, so &(*it) is the address of the value. Or did I miss something? I vote pro drink :beer:

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                Colin Leitner
                wrote on last edited by
                #19

                Correct :D! Altough I believe the questioner ment D).

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                • C Chris Losinger

                  sadly, that used up the last of my "serious" for today. time for beer. -c


                  Conservative: One who admires radicals centuries after they're dead. -- Leo C. Rosten

                  image effects!

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                  David Wulff
                  wrote on last edited by
                  #20

                  lol. :)


                  David Wulff http://www.davidwulff.co.uk

                  One 18yrs male, red and white, good condition; daily servicing required. £500 collect ono.

                  1 Reply Last reply
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                  • C Colin Leitner

                    Looking into the MSDN can open eyes! iterator overloads operator*. plain and simple. Somehow the STL trys to use references wherever possible.

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                    Chris Losinger
                    wrote on last edited by
                    #21

                    Colin Leitner wrote: plain and simple what's plain and simple? *it.menuItem // does not compile (*it).menuItem // compiles nicely -c


                    Conservative: One who admires radicals centuries after they're dead. -- Leo C. Rosten

                    image effects!

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                    • C Chris Losinger

                      Colin Leitner wrote: plain and simple what's plain and simple? *it.menuItem // does not compile (*it).menuItem // compiles nicely -c


                      Conservative: One who admires radicals centuries after they're dead. -- Leo C. Rosten

                      image effects!

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                      Colin Leitner
                      wrote on last edited by
                      #22

                      iterator is a struct. now operator* returns the value (if I understood that right). so you need it.operator*().menuItem or (*it).menuItem. This has nothing to do with any pointer syntax.

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                      • C Colin Leitner

                        iterator is a struct. now operator* returns the value (if I understood that right). so you need it.operator*().menuItem or (*it).menuItem. This has nothing to do with any pointer syntax.

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                        Chris Losinger
                        wrote on last edited by
                        #23

                        but it has a lot to do with precedence. overloading an operator, such as "*" doesn't change its precedence. -c


                        Conservative: One who admires radicals centuries after they're dead. -- Leo C. Rosten

                        image effects!

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                        • C Chris Losinger

                          but it has a lot to do with precedence. overloading an operator, such as "*" doesn't change its precedence. -c


                          Conservative: One who admires radicals centuries after they're dead. -- Leo C. Rosten

                          image effects!

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                          Colin Leitner
                          wrote on last edited by
                          #24

                          Yes but '->' won't work at all! You cannot change operator precedence at all, that's correct. a+++++b ;)

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                          • N Nemanja Trifunovic

                            The answer is C) (*it) is the value, so &(*it) is the address of the value. Or did I miss something? I vote pro drink :beer:

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                            peterchen
                            wrote on last edited by
                            #25

                            What's wrong with 'it' alone - (as long as the context indicates a valuetype * is expected)


                            You don't need to sleep to see a nightmare  Anne Clark   [sighist]

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                            • C Colin Leitner

                              Yes but '->' won't work at all! You cannot change operator precedence at all, that's correct. a+++++b ;)

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                              Chris Losinger
                              wrote on last edited by
                              #26

                              are you 100% sure of that?

                              #include <vector>

                              struct sc
                              {
                              sc(int i) {v=i;}
                              sc() {v=0;}

                              int v;
                              };
                              int main(int argc, char* argv[])
                              {

                              std::vector <sc> myvec;
                              myvec.push_back(sc(10));
                              myvec.push_back(sc(40));
                              myvec.push_back(sc(60));
                              myvec.push_back(sc(15));
                              myvec.push_back(sc(13));
                              myvec.push_back(sc(11));

                              for (std::vector<sc>::iterator it = myvec.begin(); it!=myvec.end(); it++)
                              {
                              if ((*it).v != it->v)
                              {
                              printf("%d != %d\n", (*it).v, it->v);
                              }
                              }
                              return 0;
                              }

                              cause this works fine. -c


                              Conservative: One who admires radicals centuries after they're dead. -- Leo C. Rosten

                              image effects!

                              C 1 Reply Last reply
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                              • P peterchen

                                What's wrong with 'it' alone - (as long as the context indicates a valuetype * is expected)


                                You don't need to sleep to see a nightmare  Anne Clark   [sighist]

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                                Michael Dunn
                                wrote on last edited by
                                #27

                                peterchen wrote: What's wrong with 'it' a You mean, aside from being incorrect code? ;) An iterator is an opaque data type, like say POSITION in MFC. You can't make any assumptions about it actually being a pointer to the underlying data, because iterator is not documented as such. --Mike-- Just released - RightClick-Encrypt v1.3 - Adds fast & easy file encryption to Explorer My really out-of-date homepage Sonork-100.19012 Acid_Helm

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                                • R Ryan Johnston 0

                                  I don't know anything about STL, what is an STL iterator? Having said that the only option that look reasonable is D (although other options are possible if iterators have overloaded operators). Ryan Johnston

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                                  Michael Dunn
                                  wrote on last edited by
                                  #28

                                  It's a type used to iterate (!) through the elements in an STL collection (vector, list, etc.) --Mike-- Just released - RightClick-Encrypt v1.3 - Adds fast & easy file encryption to Explorer My really out-of-date homepage Sonork-100.19012 Acid_Helm

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                                  • C Chris Losinger

                                    are you 100% sure of that?

                                    #include <vector>

                                    struct sc
                                    {
                                    sc(int i) {v=i;}
                                    sc() {v=0;}

                                    int v;
                                    };
                                    int main(int argc, char* argv[])
                                    {

                                    std::vector <sc> myvec;
                                    myvec.push_back(sc(10));
                                    myvec.push_back(sc(40));
                                    myvec.push_back(sc(60));
                                    myvec.push_back(sc(15));
                                    myvec.push_back(sc(13));
                                    myvec.push_back(sc(11));

                                    for (std::vector<sc>::iterator it = myvec.begin(); it!=myvec.end(); it++)
                                    {
                                    if ((*it).v != it->v)
                                    {
                                    printf("%d != %d\n", (*it).v, it->v);
                                    }
                                    }
                                    return 0;
                                    }

                                    cause this works fine. -c


                                    Conservative: One who admires radicals centuries after they're dead. -- Leo C. Rosten

                                    image effects!

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                                    Colin Leitner
                                    wrote on last edited by
                                    #29

                                    I'm sorry, I forgot they implemented the operator-> too (argh! operator overloading begins to suck ;)

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                                    • C Colin Leitner

                                      I'm sorry, I forgot they implemented the operator-> too (argh! operator overloading begins to suck ;)

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                                      Colin Leitner
                                      wrote on last edited by
                                      #30

                                      Clickety.I choose a random iterator type, but they all behave the same.

                                      1 Reply Last reply
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                                      • D David Stone

                                        Congrats to Christian Graus for thinking up the QOTD. I believe this is the first one I've seen from a CPian. Of course, I can't answer because I haven't a clue when it comes to STL. So I'll just leave the answering of it to the rest of you. :) David Stone It seemed similar to someone saying, "Would you like to meet my knife collection?" Ryan Johnston on Elaine's sig

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                                        Giles
                                        wrote on last edited by
                                        #31

                                        Ahh, my brain is switched off. For that past few days I've been going though interfaces/abstract classes and coding COM objects in pure C++, to gain a better understanding. Now I think I know this one, as I use them quite a bit, but I've not got the energy to make sure. brain is mush, and I've just finished watching Lord 'o' the Rings. I'm battered, and I think I'm going to have another glass of wine...... :-D(stupid grin)

                                        1 Reply Last reply
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                                        • D David Stone

                                          Congrats to Christian Graus for thinking up the QOTD. I believe this is the first one I've seen from a CPian. Of course, I can't answer because I haven't a clue when it comes to STL. So I'll just leave the answering of it to the rest of you. :) David Stone It seemed similar to someone saying, "Would you like to meet my knife collection?" Ryan Johnston on Elaine's sig

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                                          Todd Smith
                                          wrote on last edited by
                                          #32

                                          What about option E) const_cast<Type&>(*it).Foo() ? Otherwise you're editing a copy of the object. Todd Smith

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