Skip to content
  • Categories
  • Recent
  • Tags
  • Popular
  • Users
  • Groups
  • Search
  • Get Qt Extensions
  • Unsolved
Collapse
Brand Logo
  1. Home
  2. Special Interest Groups
  3. C++ Gurus
  4. Boolean in C
Forum Updated to NodeBB v4.3 + New Features

Boolean in C

Scheduled Pinned Locked Moved Unsolved C++ Gurus
34 Posts 11 Posters 7.6k Views 6 Watching
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • sierdzioS sierdzio

    I find it much easier to understand if something is false when I see if (something == false) than when I see if (!something). Especially in longer expressions it is very easy to miss a single character like ! and read the code wrong.

    JonBJ Online
    JonBJ Online
    JonB
    wrote on last edited by JonB
    #13

    @sierdzio
    I see a personal-choice-disagreement debate looming... ;-)

    I do agree it is "unfortunate" that C chose just that little ! for "not". But personally I never write == false or != false, because I would never "say" that in RL....

    1 Reply Last reply
    0
    • sierdzioS sierdzio

      I find it much easier to understand if something is false when I see if (something == false) than when I see if (!something). Especially in longer expressions it is very easy to miss a single character like ! and read the code wrong.

      J.HilkJ Offline
      J.HilkJ Offline
      J.Hilk
      Moderators
      wrote on last edited by
      #14

      @sierdzio , @JonB

      are you guys aware, that not is a valid keyword in c++ ?

      https://en.cppreference.com/w/cpp/keyword/not


      Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


      Q: What's that?
      A: It's blue light.
      Q: What does it do?
      A: It turns blue.

      JonBJ sierdzioS Kent-DorfmanK 3 Replies Last reply
      1
      • J.HilkJ J.Hilk

        @sierdzio , @JonB

        are you guys aware, that not is a valid keyword in c++ ?

        https://en.cppreference.com/w/cpp/keyword/not

        JonBJ Online
        JonBJ Online
        JonB
        wrote on last edited by JonB
        #15

        @J-Hilk
        Yup. And it's devil's-spawn! ;-) [Same for and & or. If I wanted to program in Python or Pascal I would have picked that.] I would never use that, as "nobody" (most people) else uses it or knows about it, so I would regard it as an anti-pattern!

        1 Reply Last reply
        0
        • J.HilkJ J.Hilk

          @sierdzio , @JonB

          are you guys aware, that not is a valid keyword in c++ ?

          https://en.cppreference.com/w/cpp/keyword/not

          sierdzioS Offline
          sierdzioS Offline
          sierdzio
          Moderators
          wrote on last edited by
          #16

          @J-Hilk said in Boolean in C:

          @sierdzio , @JonB

          are you guys aware, that not is a valid keyword in c++ ?

          https://en.cppreference.com/w/cpp/keyword/not

          Yes but not in all compilers :-( MSVC does not recognize it.

          (Z(:^

          JonBJ J.HilkJ 2 Replies Last reply
          1
          • sierdzioS sierdzio

            @J-Hilk said in Boolean in C:

            @sierdzio , @JonB

            are you guys aware, that not is a valid keyword in c++ ?

            https://en.cppreference.com/w/cpp/keyword/not

            Yes but not in all compilers :-( MSVC does not recognize it.

            JonBJ Online
            JonBJ Online
            JonB
            wrote on last edited by
            #17

            @sierdzio
            Good, but are you sure? Since it is valid since C99, I would have thought that MSVC would accept those?

            sierdzioS 1 Reply Last reply
            0
            • JonBJ JonB

              @sierdzio
              Good, but are you sure? Since it is valid since C99, I would have thought that MSVC would accept those?

              sierdzioS Offline
              sierdzioS Offline
              sierdzio
              Moderators
              wrote on last edited by
              #18

              @JonB said in Boolean in C:

              @sierdzio
              Good, but are you sure? Since it is valid since C99, I would have thought that MSVC would accept those?

              Last time I tried was last year. Clang, GCC all are 100% fine with it, MSVC was throwing errors.

              I now see it's supposed to be defined in some iso646.h header, I never included it, perhaps that's the reason.

              (Z(:^

              JonBJ 1 Reply Last reply
              1
              • sierdzioS sierdzio

                @J-Hilk said in Boolean in C:

                @sierdzio , @JonB

                are you guys aware, that not is a valid keyword in c++ ?

                https://en.cppreference.com/w/cpp/keyword/not

                Yes but not in all compilers :-( MSVC does not recognize it.

                J.HilkJ Offline
                J.HilkJ Offline
                J.Hilk
                Moderators
                wrote on last edited by
                #19

                @sierdzio said in Boolean in C:

                Yes but not in all compilers :-( MSVC does not recognize it.

                VS been nonconforming! 😱 Color me surprised 😉


                Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                Q: What's that?
                A: It's blue light.
                Q: What does it do?
                A: It turns blue.

                1 Reply Last reply
                1
                • sierdzioS sierdzio

                  @JonB said in Boolean in C:

                  @sierdzio
                  Good, but are you sure? Since it is valid since C99, I would have thought that MSVC would accept those?

                  Last time I tried was last year. Clang, GCC all are 100% fine with it, MSVC was throwing errors.

                  I now see it's supposed to be defined in some iso646.h header, I never included it, perhaps that's the reason.

                  JonBJ Online
                  JonBJ Online
                  JonB
                  wrote on last edited by
                  #20

                  @sierdzio
                  If one has to include a header file for them, makes me wonder if they are not "part of the language", just should be available if you include the header. Are they just #defines in that file??

                  sierdzioS 1 Reply Last reply
                  1
                  • JonBJ JonB

                    @sierdzio
                    If one has to include a header file for them, makes me wonder if they are not "part of the language", just should be available if you include the header. Are they just #defines in that file??

                    sierdzioS Offline
                    sierdzioS Offline
                    sierdzio
                    Moderators
                    wrote on last edited by
                    #21

                    @JonB said in Boolean in C:

                    @sierdzio
                    If one has to include a header file for them, makes me wonder if they are not "part of the language", just should be available if you include the header. Are they just #defines in that file??

                    yup :D

                    #define and    &&
                    #define and_eq &=
                    #define bitand &
                    #define bitor  |
                    #define compl  ~
                    #define not    !
                    #define not_eq !=
                    #define or     ||
                    #define or_eq  |=
                    #define xor    ^
                    #define xor_eq ^=
                    

                    They are not actual C++ language reserved keywords.

                    (Z(:^

                    JonBJ 1 Reply Last reply
                    1
                    • sierdzioS sierdzio

                      @JonB said in Boolean in C:

                      @sierdzio
                      If one has to include a header file for them, makes me wonder if they are not "part of the language", just should be available if you include the header. Are they just #defines in that file??

                      yup :D

                      #define and    &&
                      #define and_eq &=
                      #define bitand &
                      #define bitor  |
                      #define compl  ~
                      #define not    !
                      #define not_eq !=
                      #define or     ||
                      #define or_eq  |=
                      #define xor    ^
                      #define xor_eq ^=
                      

                      They are not actual C++ language reserved keywords.

                      JonBJ Online
                      JonBJ Online
                      JonB
                      wrote on last edited by
                      #22

                      @sierdzio
                      Hmmmm.... So does gcc have these in some header file, or does their C++ actually have them as reserved? It does have an iso646.h file, with the #defines, yet you said they worked for you in gcc without you explicitly including that? Does it include it automatically or from something else?

                      J.HilkJ 1 Reply Last reply
                      1
                      • JonBJ JonB

                        @sierdzio
                        Hmmmm.... So does gcc have these in some header file, or does their C++ actually have them as reserved? It does have an iso646.h file, with the #defines, yet you said they worked for you in gcc without you explicitly including that? Does it include it automatically or from something else?

                        J.HilkJ Offline
                        J.HilkJ Offline
                        J.Hilk
                        Moderators
                        wrote on last edited by
                        #23

                        @JonB said in Boolean in C:

                        worked for you in gcc without you explicitly including that? Does it include it automatically or from something else

                        This header was originally in the C standard library as <iso646.h>.
                        Compatibility header, in C defines alternative operator representations which are keywords in C++.
                        This means that in a conforming implementation, including this header has no effect.
                        

                        gcc has mostly a conforming implementation, at least in this regard


                        Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                        Q: What's that?
                        A: It's blue light.
                        Q: What does it do?
                        A: It turns blue.

                        JonBJ 1 Reply Last reply
                        2
                        • J.HilkJ J.Hilk

                          @JonB said in Boolean in C:

                          worked for you in gcc without you explicitly including that? Does it include it automatically or from something else

                          This header was originally in the C standard library as <iso646.h>.
                          Compatibility header, in C defines alternative operator representations which are keywords in C++.
                          This means that in a conforming implementation, including this header has no effect.
                          

                          gcc has mostly a conforming implementation, at least in this regard

                          JonBJ Online
                          JonBJ Online
                          JonB
                          wrote on last edited by
                          #24

                          @J-Hilk said in Boolean in C:

                          This header was originally in the C standard library as <iso646.h>.

                          So what file is this in, which you say is included automatically?

                          jsulmJ J.HilkJ 2 Replies Last reply
                          0
                          • JonBJ JonB

                            @J-Hilk said in Boolean in C:

                            This header was originally in the C standard library as <iso646.h>.

                            So what file is this in, which you say is included automatically?

                            jsulmJ Offline
                            jsulmJ Offline
                            jsulm
                            Lifetime Qt Champion
                            wrote on last edited by
                            #25

                            @JonB said in Boolean in C:

                            which you say is included automatically?

                            My understanding is that it is NOT included automatically in conforming C++ implementations because those understand these words as keywords and don't need this header file (which is only there for compatibility reasons).

                            https://forum.qt.io/topic/113070/qt-code-of-conduct

                            JonBJ 1 Reply Last reply
                            2
                            • JonBJ JonB

                              @J-Hilk said in Boolean in C:

                              This header was originally in the C standard library as <iso646.h>.

                              So what file is this in, which you say is included automatically?

                              J.HilkJ Offline
                              J.HilkJ Offline
                              J.Hilk
                              Moderators
                              wrote on last edited by
                              #26

                              @JonB I'm talking about the iso646.h @sierdzio mentioned

                              https://en.cppreference.com/w/cpp/header/ciso646

                              Probably the reason why MSVC doesn't have those as keywords but requires this header is, IIRC, that it doesn't have/use a dedicated c compiler for c headers and it would break legacy stuff if those were used as keywords


                              Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                              Q: What's that?
                              A: It's blue light.
                              Q: What does it do?
                              A: It turns blue.

                              1 Reply Last reply
                              1
                              • jsulmJ jsulm

                                @JonB said in Boolean in C:

                                which you say is included automatically?

                                My understanding is that it is NOT included automatically in conforming C++ implementations because those understand these words as keywords and don't need this header file (which is only there for compatibility reasons).

                                JonBJ Online
                                JonBJ Online
                                JonB
                                wrote on last edited by
                                #27

                                @jsulm
                                Mine too. But I quote from @sierdzio above:

                                Last time I tried was last year. Clang, GCC all are 100% fine with it, MSVC was throwing errors.

                                I now see it's supposed to be defined in some iso646.h header, I never included it, perhaps that's the reason.

                                My question is (should be) aimed at him: he says it worked automatically in GCC/Clang (but not MSVC) with no #include from him, that's what I'm trying to understand.

                                1 Reply Last reply
                                0
                                • fcarneyF Offline
                                  fcarneyF Offline
                                  fcarney
                                  wrote on last edited by
                                  #28

                                  I know Boolean is someone's name.
                                  But it kind of look like a diet fad to scare people skinny: boo-lean.

                                  C++ is a perfectly valid school of magic.

                                  jsulmJ 1 Reply Last reply
                                  0
                                  • fcarneyF fcarney

                                    I know Boolean is someone's name.
                                    But it kind of look like a diet fad to scare people skinny: boo-lean.

                                    jsulmJ Offline
                                    jsulmJ Offline
                                    jsulm
                                    Lifetime Qt Champion
                                    wrote on last edited by
                                    #29

                                    @fcarney You mean Anne Boleyn, one of the wifes of king Henry VI which was executed. She was mother of Elisabeth I :-)

                                    https://forum.qt.io/topic/113070/qt-code-of-conduct

                                    jeremy_kJ 1 Reply Last reply
                                    0
                                    • jsulmJ jsulm

                                      @fcarney You mean Anne Boleyn, one of the wifes of king Henry VI which was executed. She was mother of Elisabeth I :-)

                                      jeremy_kJ Offline
                                      jeremy_kJ Offline
                                      jeremy_k
                                      wrote on last edited by
                                      #30

                                      @jsulm said in Boolean in C:

                                      @fcarney You mean Anne Boleyn, one of the wifes of king Henry VI which was executed. She was mother of Elisabeth I :-)

                                      Ha! I'm not sure what a Boleyn variable would be. Dangerous in some manner.

                                      Presumably @fcarney is referring to George Boole.

                                      Asking a question about code? http://eel.is/iso-c++/testcase/

                                      Kent-DorfmanK 1 Reply Last reply
                                      1
                                      • J.HilkJ J.Hilk

                                        @sierdzio , @JonB

                                        are you guys aware, that not is a valid keyword in c++ ?

                                        https://en.cppreference.com/w/cpp/keyword/not

                                        Kent-DorfmanK Offline
                                        Kent-DorfmanK Offline
                                        Kent-Dorfman
                                        wrote on last edited by
                                        #31

                                        @J-Hilk said in Boolean in C:

                                        are you guys aware, that not is a valid keyword in c++ ?

                                        Heretic!
                                        and the discussion is about C. ;^P

                                        But to the point about superfluous comparisons: I guess is comes down to whether you understand the grammar. If you understand that all comparison operations evaluate to a boolean value (zero, or not zero) then it should become evident that explicit comparisons of booleans to a constant is redundant.

                                        1 Reply Last reply
                                        0
                                        • jeremy_kJ jeremy_k

                                          @jsulm said in Boolean in C:

                                          @fcarney You mean Anne Boleyn, one of the wifes of king Henry VI which was executed. She was mother of Elisabeth I :-)

                                          Ha! I'm not sure what a Boleyn variable would be. Dangerous in some manner.

                                          Presumably @fcarney is referring to George Boole.

                                          Kent-DorfmanK Offline
                                          Kent-DorfmanK Offline
                                          Kent-Dorfman
                                          wrote on last edited by
                                          #32

                                          @jeremy_k said in Boolean in C:

                                          Ha! I'm not sure what a Boleyn variable would be. Dangerous in some manner.

                                          I guess technically I AM, being a decendent of Mary Boleyn...as for being dangerous... :^D

                                          JonBJ 1 Reply Last reply
                                          0

                                          • Login

                                          • Login or register to search.
                                          • First post
                                            Last post
                                          0
                                          • Categories
                                          • Recent
                                          • Tags
                                          • Popular
                                          • Users
                                          • Groups
                                          • Search
                                          • Get Qt Extensions
                                          • Unsolved