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Forum Update on Monday, May 27th 2025

How to run a C++ code in Qt?

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  • K kshegunov
    23 Feb 2016, 10:25

    @Rela said:

    There are ... in the "main.cpp" already.

    But obviously these headers are not present in mainwindow.h, whence the compile errors. The compiler doesn't know heck about ostream when processing the mainwindow.h and it's whining ...

    Kind regards.

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    Rela
    wrote on 23 Feb 2016, 12:12 last edited by
    #109

    @kshegunov
    Thanks. Do you know what else I can do except adding ```

    #include <stdio.h>
    

    to the "mainwindow.h"?

    K 1 Reply Last reply 23 Feb 2016, 12:16
    0
    • R Rela
      23 Feb 2016, 12:12

      @kshegunov
      Thanks. Do you know what else I can do except adding ```

      #include <stdio.h>
      

      to the "mainwindow.h"?

      K Offline
      K Offline
      kshegunov
      Moderators
      wrote on 23 Feb 2016, 12:16 last edited by
      #110

      @Rela

      Add the aforementioned headers to the mainwindow.h:

      #include <iostream>
      #include <fstream>
      #include <ostream>
      
      using namespace std;
      

      Otherwise the compiler will not know what ostream is.

      Read and abide by the Qt Code of Conduct

      R 1 Reply Last reply 23 Feb 2016, 12:48
      0
      • K kshegunov
        23 Feb 2016, 12:16

        @Rela

        Add the aforementioned headers to the mainwindow.h:

        #include <iostream>
        #include <fstream>
        #include <ostream>
        
        using namespace std;
        

        Otherwise the compiler will not know what ostream is.

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        Rela
        wrote on 23 Feb 2016, 12:48 last edited by
        #111

        @kshegunov
        Done, but here are the errors cleaned again ;)

        K 1 Reply Last reply 23 Feb 2016, 12:57
        0
        • R Rela
          23 Feb 2016, 12:48

          @kshegunov
          Done, but here are the errors cleaned again ;)

          K Offline
          K Offline
          kshegunov
          Moderators
          wrote on 23 Feb 2016, 12:57 last edited by
          #112

          @Rela
          I'm sorry but I have no idea what's happening, with the deletions and without a complete code snippet this is just turning into a guessing game. Not to mention the preprocessor directives, whose expansions I have no way of deducing. The errors have obviously changed and they are at compile-time, so focus on that and try to resolve the type mismatches.

          Read and abide by the Qt Code of Conduct

          R 1 Reply Last reply 23 Feb 2016, 13:31
          0
          • K kshegunov
            23 Feb 2016, 12:57

            @Rela
            I'm sorry but I have no idea what's happening, with the deletions and without a complete code snippet this is just turning into a guessing game. Not to mention the preprocessor directives, whose expansions I have no way of deducing. The errors have obviously changed and they are at compile-time, so focus on that and try to resolve the type mismatches.

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            Rela
            wrote on 23 Feb 2016, 13:31 last edited by
            #113

            @kshegunov
            The problem is not related to the code. The C++ code works properly in MV and also it worked in Qt creator before and gave the results in "Application Outputs" with Qt5.5 and MV 2013. The problem happened, when I start working with MV 2015 and Qt5.6 beta.
            I just did the previous way and added all C++ files to the Qt project files. Do you have any idea about the ```

            error: dependent '..\C++' does not exist.
            
            K 1 Reply Last reply 23 Feb 2016, 13:41
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            • R Rela
              23 Feb 2016, 13:31

              @kshegunov
              The problem is not related to the code. The C++ code works properly in MV and also it worked in Qt creator before and gave the results in "Application Outputs" with Qt5.5 and MV 2013. The problem happened, when I start working with MV 2015 and Qt5.6 beta.
              I just did the previous way and added all C++ files to the Qt project files. Do you have any idea about the ```

              error: dependent '..\C++' does not exist.
              
              K Offline
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              kshegunov
              Moderators
              wrote on 23 Feb 2016, 13:41 last edited by
              #114

              @Rela
              I have never seen that error, but if I had to guess probably a folder can't be found by qmake. Inspect your project file, and make sure all folders/files exist. Then rerun qmake and then do a full rebuild. Additionally, don't use backslashes for your paths when working with qmake, use *nix-style paths, for example: C:/somefolder/somefile.cpp

              Read and abide by the Qt Code of Conduct

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              • S Offline
                S Offline
                SGaist
                Lifetime Qt Champion
                wrote on 23 Feb 2016, 20:41 last edited by
                #115

                Do you have something containing "C++" anywhere in your .pro file ?

                Interested in AI ? www.idiap.ch
                Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                R 1 Reply Last reply 24 Feb 2016, 13:51
                0
                • S SGaist
                  23 Feb 2016, 20:41

                  Do you have something containing "C++" anywhere in your .pro file ?

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                  Rela
                  wrote on 24 Feb 2016, 13:51 last edited by
                  #116

                  @SGaist
                  Yes, I had something like this in PS8, because I added the C++ project header and source files through the "../C++ projects/po... /" path. But, now I removed the space of "C++ projects" (because maybe it makes problem), and changed the path withoutspace. PS10 Qt project .pro file is this
                  Now the error is this

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                  • jsulmJ Offline
                    jsulmJ Offline
                    jsulm
                    Lifetime Qt Champion
                    wrote on 25 Feb 2016, 06:37 last edited by
                    #117

                    What is char.h?

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

                    R 1 Reply Last reply 25 Feb 2016, 11:15
                    0
                    • jsulmJ jsulm
                      25 Feb 2016, 06:37

                      What is char.h?

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                      Rela
                      wrote on 25 Feb 2016, 11:15 last edited by Rela
                      #118

                      @jsulm
                      It was

                      #include <tchar.h>
                      

                      in the C++ code, but it had given the errors like

                      'void PS... (char *)': cannot convert argument 1 from 'const char [37]' to 'char *'
                      

                      and I changed it to "char".
                      I think its related to the main function in "main.cpp"

                      int main(int argc, char* argv[])
                      {
                      
                      K 1 Reply Last reply 25 Feb 2016, 12:10
                      0
                      • jsulmJ Offline
                        jsulmJ Offline
                        jsulm
                        Lifetime Qt Champion
                        wrote on 25 Feb 2016, 11:47 last edited by
                        #119

                        How is it related to main?
                        char is a native data type in C and C++, you do not have to include any header file to use it. So just remove this include.
                        This error:

                        'void PS... (char *)': cannot convert argument 1 from 'const char [37]' to 'char *'
                        

                        You got probably because you're passing a const char string as parameter to a function which expects a non const char string:

                        void PS... (char *param);
                        then you call
                        PS...("a string");
                        

                        Do it like this:

                        char *param = "a string";
                        PS...(param);
                        

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

                        1 Reply Last reply
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                        • R Rela
                          25 Feb 2016, 11:15

                          @jsulm
                          It was

                          #include <tchar.h>
                          

                          in the C++ code, but it had given the errors like

                          'void PS... (char *)': cannot convert argument 1 from 'const char [37]' to 'char *'
                          

                          and I changed it to "char".
                          I think its related to the main function in "main.cpp"

                          int main(int argc, char* argv[])
                          {
                          
                          K Offline
                          K Offline
                          kshegunov
                          Moderators
                          wrote on 25 Feb 2016, 12:10 last edited by
                          #120

                          @Rela

                          'void PS... (char *)': cannot convert argument 1 from 'const char [37]' to 'char *'

                          The error is because you're passing const char * const to a function expecting char * and the compiler doesn't know how to (safely) convert the argument. My advice is: rework your function to accept non-mutable arguments if possible, if not - fix the type mismatch. @jsulm already pointed out that you shouldn't include headers you're not going to need, unless massive compilation times is something you're after.

                          Kind regards.

                          Read and abide by the Qt Code of Conduct

                          1 Reply Last reply
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                          • R Offline
                            R Offline
                            Rela
                            wrote on 29 Mar 2016, 10:45 last edited by Rela
                            #121

                            Hi, the previous error was solved. I wanted to have a C++ code results in widget. For reminding in brief, I created a Qt widget project, and I added the C++ code including header and source files to the project. I copied the main.cpp C++ codes in the Qt main.cpp file.

                            The error was ```

                            void PS... (char *)': cannot convert argument 1 from 'const char [37]' to 'char *
                            

                            I changed the definition of the function:

                            void PS... (char *_sth)
                            

                            to

                            void PS... (const char *_sth) 
                            

                            and it doesn't give the error. But, now I want to have some values as result in Application Output , but instead of the non-zero values, they are all zero.
                            The input data are read from a model.txt file. The path of the text file was also added in the "project" > run of "Desktop Qt 5.6 MSVC2015 64 bit" > "Arguments". Do you know if it is related to the reading input data or not?

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                            • jsulmJ Offline
                              jsulmJ Offline
                              jsulm
                              Lifetime Qt Champion
                              wrote on 29 Mar 2016, 12:58 last edited by
                              #122

                              How do you read model.txt file?
                              Is this file found?
                              Do you have any errors while reading it?
                              Why don't just debug and see what happens?

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

                              R 1 Reply Last reply 1 Apr 2016, 11:33
                              0
                              • jsulmJ jsulm
                                29 Mar 2016, 12:58

                                How do you read model.txt file?
                                Is this file found?
                                Do you have any errors while reading it?
                                Why don't just debug and see what happens?

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                                Rela
                                wrote on 1 Apr 2016, 11:33 last edited by
                                #123

                                @jsulm
                                In the code, it read using ```

                                bool ReadModelData(istream &in, functionname &_PS) ...
                                ...
                                ReadModelData (fin,s)
                                ...
                                

                                The path of the text file was added in the "project" > run of "Desktop Qt 5.6 MSVC2015 64 bit" > "Arguments". File path
                                When I debug it just show in the Application output:

                                Debugging starts
                                Debugging has finished
                                

                                and when run the code the results are cpu=0 z=0 ... while they should be some non-zero.

                                1 Reply Last reply
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