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QString Error

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  • kshegunovK Offline
    kshegunovK Offline
    kshegunov
    Moderators
    wrote on last edited by
    #2

    Hello,
    This is not a Qt problem, your C++ syntax is wrong. Function arguments (constructors included) are surrounded by parenthesis, not with curly braces.

    Kind regards.

    Read and abide by the Qt Code of Conduct

    1 Reply Last reply
    0
    • M Offline
      M Offline
      marvic_39
      wrote on last edited by marvic_39
      #3

      Thank you for replay, i changed to circle brackets

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

      still It flashing error again.

      /home/cpp/cap.h:108: error: expected identifier before string constant
      /home/cpp/cap.h:108: error: expected ',' or '...' before string constant```
      
      Thank You.
      1 Reply Last reply
      0
      • mrjjM Offline
        mrjjM Offline
        mrjj
        Lifetime Qt Champion
        wrote on last edited by
        #4

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

        M 1 Reply Last reply
        0
        • 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 Online
                            hskoglundH Online
                            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
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                            • 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
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                                • 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
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