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QString Error

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  • mrjjM mrjj

    @marvic_39 said:
    and you do have
    #include <QString>
    ?

    M Offline
    M Offline
    marvic_39
    wrote on last edited by
    #5

    @mrjj

    Yes, #include <QString>
    As well
    #include <QtCore>

    mrjjM 1 Reply Last reply
    0
    • M marvic_39

      @mrjj

      Yes, #include <QString>
      As well
      #include <QtCore>

      mrjjM Offline
      mrjjM Offline
      mrjj
      Lifetime Qt Champion
      wrote on last edited by
      #6

      @marvic_39
      can it be error from lines above it as

      #include <QString>
      QString settingsFile("/boot/settings.json");
      

      surely compiles.

      check if lines above has ; in the end

      M 1 Reply Last reply
      0
      • mrjjM mrjj

        @marvic_39
        can it be error from lines above it as

        #include <QString>
        QString settingsFile("/boot/settings.json");
        

        surely compiles.

        check if lines above has ; in the end

        M Offline
        M Offline
        marvic_39
        wrote on last edited by marvic_39
        #7

        @mrjj

        This is the statement, Still errors

        QString settingsFile("/neet/one.json");
        
        

        And header
        #include <QString>

        1 Reply Last reply
        0
        • kshegunovK Offline
          kshegunovK Offline
          kshegunov
          Moderators
          wrote on last edited by
          #8

          Ok, the statement is valid. Where is this located, in your header? It's not a good idea to declare variables in headers. Also, how do you compile (what environment/compiler) are you using?

          Read and abide by the Qt Code of Conduct

          M 1 Reply Last reply
          1
          • kshegunovK kshegunov

            Ok, the statement is valid. Where is this located, in your header? It's not a good idea to declare variables in headers. Also, how do you compile (what environment/compiler) are you using?

            M Offline
            M Offline
            marvic_39
            wrote on last edited by
            #9

            @kshegunov

            Where you declare variables?

            kshegunovK 1 Reply Last reply
            0
            • M marvic_39

              @kshegunov

              Where you declare variables?

              kshegunovK Offline
              kshegunovK Offline
              kshegunov
              Moderators
              wrote on last edited by kshegunov
              #10

              @marvic_39
              Usually where you use them, in functions or blocks. If you have a global variable then it is declared in the .cpp file, thus you don't get the same symbol in multiple translation units (.o files resulting from compilation). It is safe to put extern declarations in header files, because they do not amount to a variable, but are only information for the compiler (and linker).
              This most certainly is a C++ problem. My suggestion is to read up a bit more on C++ to have a better grasp on where and for what memory is allocated. That being said, without a bit more of code and/or information on the problem you're facing I fear I wouldn't be of much help.

              Here are some resources you could use, if you wish:
              http://www.learncpp.com/cpp-tutorial/13-a-first-look-at-variables-initialization-and-assignment/
              http://www.learncpp.com/cpp-tutorial/41-blocks-compound-statements/
              http://www.learncpp.com/cpp-tutorial/42-global-variables/
              https://en.wikipedia.org/wiki/Call_stack

              Read and abide by the Qt Code of Conduct

              M 1 Reply Last reply
              0
              • kshegunovK kshegunov

                @marvic_39
                Usually where you use them, in functions or blocks. If you have a global variable then it is declared in the .cpp file, thus you don't get the same symbol in multiple translation units (.o files resulting from compilation). It is safe to put extern declarations in header files, because they do not amount to a variable, but are only information for the compiler (and linker).
                This most certainly is a C++ problem. My suggestion is to read up a bit more on C++ to have a better grasp on where and for what memory is allocated. That being said, without a bit more of code and/or information on the problem you're facing I fear I wouldn't be of much help.

                Here are some resources you could use, if you wish:
                http://www.learncpp.com/cpp-tutorial/13-a-first-look-at-variables-initialization-and-assignment/
                http://www.learncpp.com/cpp-tutorial/41-blocks-compound-statements/
                http://www.learncpp.com/cpp-tutorial/42-global-variables/
                https://en.wikipedia.org/wiki/Call_stack

                M Offline
                M Offline
                marvic_39
                wrote on last edited by
                #11

                @kshegunov

                I am aware of C++, It looks good, If you provide a solution, how to solve this single statement. You do not need to be proficient.

                RatzzR 1 Reply Last reply
                0
                • M marvic_39

                  @kshegunov

                  I am aware of C++, It looks good, If you provide a solution, how to solve this single statement. You do not need to be proficient.

                  RatzzR Offline
                  RatzzR Offline
                  Ratzz
                  wrote on last edited by
                  #12

                  @marvic_39
                  Might be problem with GCC.Check your Gcc version .

                  --Alles ist gut.

                  M 1 Reply Last reply
                  0
                  • RatzzR Ratzz

                    @marvic_39
                    Might be problem with GCC.Check your Gcc version .

                    M Offline
                    M Offline
                    marvic_39
                    wrote on last edited by
                    #13

                    @Ratzz

                    Other apps and examples are working fine and executing properly.

                    1 Reply Last reply
                    0
                    • hskoglundH Offline
                      hskoglundH Offline
                      hskoglund
                      wrote on last edited by
                      #14

                      Hi, just guessing, but if that line is inside a class declaration (not outside) then you'll get that 108 error, for example:

                      class MyClass {
                      ...
                      QString settingsFile("/boot/settings.json");
                      ...
                      };
                      

                      you could try

                      class MyClass {
                      ...
                      QString settingsFile = "/boot/settings.json";
                      ...
                      };
                      
                      M 1 Reply Last reply
                      0
                      • hskoglundH hskoglund

                        Hi, just guessing, but if that line is inside a class declaration (not outside) then you'll get that 108 error, for example:

                        class MyClass {
                        ...
                        QString settingsFile("/boot/settings.json");
                        ...
                        };
                        

                        you could try

                        class MyClass {
                        ...
                        QString settingsFile = "/boot/settings.json";
                        ...
                        };
                        
                        M Offline
                        M Offline
                        marvic_39
                        wrote on last edited by
                        #15

                        @hskoglund

                        Yes, tried that statement too. Here it's flashing error.

                        QString settingsFile = "/neet/one.json";
                        
                        /home/cpp/cap.h:109: sorry, unimplemented: non-static data member initializers
                        
                        /home/cpp/cap.h:109: error: in-class initialization of static data member 'str' of non-literal type
                        
                        1 Reply Last reply
                        0
                        • RatzzR Offline
                          RatzzR Offline
                          Ratzz
                          wrote on last edited by
                          #16

                          @hskoglund
                          What is your GCC version ? less than 4.7?

                          --Alles ist gut.

                          M 2 Replies Last reply
                          0
                          • RatzzR Ratzz

                            @hskoglund
                            What is your GCC version ? less than 4.7?

                            M Offline
                            M Offline
                            marvic_39
                            wrote on last edited by
                            #17

                            @Ratzz

                            gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3
                            

                            I cross compiled Linux, OpenCV, FFmpeg Qt Raspi and many other apps never faced a compiler problems.

                            Should this look like compiler version problem?

                            RatzzR 1 Reply Last reply
                            0
                            • M marvic_39

                              @Ratzz

                              gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3
                              

                              I cross compiled Linux, OpenCV, FFmpeg Qt Raspi and many other apps never faced a compiler problems.

                              Should this look like compiler version problem?

                              RatzzR Offline
                              RatzzR Offline
                              Ratzz
                              wrote on last edited by Ratzz
                              #18

                              @marvic_39 said:
                              But Non static data member initializers available only for GCC >4.7 . Check this . Check the GCC support docs.

                              --Alles ist gut.

                              M 1 Reply Last reply
                              1
                              • RatzzR Ratzz

                                @marvic_39 said:
                                But Non static data member initializers available only for GCC >4.7 . Check this . Check the GCC support docs.

                                M Offline
                                M Offline
                                marvic_39
                                wrote on last edited by
                                #19

                                @Ratzz

                                Thank you, Ok, Will check with updated GCC version greater than 4.7.

                                1 Reply Last reply
                                0
                                • RatzzR Ratzz

                                  @hskoglund
                                  What is your GCC version ? less than 4.7?

                                  M Offline
                                  M Offline
                                  marvic_39
                                  wrote on last edited by
                                  #20

                                  @Ratzz

                                  Installed, Still flashing errors.

                                  gcc (Ubuntu/Linaro 4.7.3-2ubuntu1~12.04) 4.7.3
                                  
                                  108   QString settingsFile("Hello");
                                  109   QString str="/neet/one.json";
                                  
                                  /home/cpp/app.h:108: error: expected identifier before string constant
                                  /home/cpp/app.h:108: error: expected ',' or '...' before string constant
                                  
                                  /home//cpp/app.h:109: sorry, unimplemented: non-static data member initializers
                                  /home/cpp/app.h:109: error: in-class initialization of static data member 'str' of non-literal type
                                  

                                  In QT creator it show this, is this correct.

                                  Qt Creator 3.5.1 (opensource)
                                  Based on Qt 5.5.1 (GCC 4.9.1 20140922 (Red Hat 4.9.1-10), 32 bit)

                                  Built on Oct 13 2015 07:38:32

                                  RatzzR 1 Reply Last reply
                                  0
                                  • M marvic_39

                                    @Ratzz

                                    Installed, Still flashing errors.

                                    gcc (Ubuntu/Linaro 4.7.3-2ubuntu1~12.04) 4.7.3
                                    
                                    108   QString settingsFile("Hello");
                                    109   QString str="/neet/one.json";
                                    
                                    /home/cpp/app.h:108: error: expected identifier before string constant
                                    /home/cpp/app.h:108: error: expected ',' or '...' before string constant
                                    
                                    /home//cpp/app.h:109: sorry, unimplemented: non-static data member initializers
                                    /home/cpp/app.h:109: error: in-class initialization of static data member 'str' of non-literal type
                                    

                                    In QT creator it show this, is this correct.

                                    Qt Creator 3.5.1 (opensource)
                                    Based on Qt 5.5.1 (GCC 4.9.1 20140922 (Red Hat 4.9.1-10), 32 bit)

                                    Built on Oct 13 2015 07:38:32

                                    RatzzR Offline
                                    RatzzR Offline
                                    Ratzz
                                    wrote on last edited by Ratzz
                                    #21

                                    @marvic_39
                                    Are you doing this inside the structure? QString settingsFile("Hello");
                                    Is the error at line 108 bec of this ?

                                    --Alles ist gut.

                                    M 1 Reply Last reply
                                    0
                                    • RatzzR Ratzz

                                      @marvic_39
                                      Are you doing this inside the structure? QString settingsFile("Hello");
                                      Is the error at line 108 bec of this ?

                                      M Offline
                                      M Offline
                                      marvic_39
                                      wrote on last edited by marvic_39
                                      #22

                                      @Ratzz

                                      I cleaned all GCC versions and activated 4.7
                                      Now it's compiled and executed my app.

                                      QString settingsFile{"neet/One.json"};
                                      

                                      Very strange about the brackets () and {}

                                      Thank You guys, it's GCC 4.7 made the difference.

                                      RatzzR 1 Reply Last reply
                                      0
                                      • M marvic_39

                                        @Ratzz

                                        I cleaned all GCC versions and activated 4.7
                                        Now it's compiled and executed my app.

                                        QString settingsFile{"neet/One.json"};
                                        

                                        Very strange about the brackets () and {}

                                        Thank You guys, it's GCC 4.7 made the difference.

                                        RatzzR Offline
                                        RatzzR Offline
                                        Ratzz
                                        wrote on last edited by
                                        #23

                                        @marvic_39
                                        Once your problem is solved please use the Topic Tools button to mark as Solved.
                                        Thank you!

                                        --Alles ist gut.

                                        1 Reply Last reply
                                        0
                                        • kshegunovK Offline
                                          kshegunovK Offline
                                          kshegunov
                                          Moderators
                                          wrote on last edited by
                                          #24

                                          Ok. I think I get what your problem was. In all probability C++11 is enabled by default in GCC 4.7 (on your distribution), that is why I asked what compiler and environment you're using. Here is the relevant link:
                                          http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2008/n2756.htm
                                          That being said, without the non-static data member initializers supported by the compiler you are obliged to initialize the object in your class' constructor and cannot do it in its declaration. Meaning that if you compile the code on another platform and/or compiler that does not have the C++11 standard enabled you'll get similar errors.

                                          Read and abide by the Qt Code of Conduct

                                          1 Reply Last reply
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