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Forum Update on Tuesday, May 27th 2025

problem with System()

Scheduled Pinned Locked Moved Unsolved General and Desktop
system commandsystem
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  • AlvaroSA AlvaroS

    @mrjj Yes thanks!! See my last post. Thanks again. It gives me Unknow error...

    mrjjM Offline
    mrjjM Offline
    mrjj
    Lifetime Qt Champion
    wrote on last edited by
    #26

    @AlvaroS

    " This is the default return value of error()."

    You do call it AFTER u call
    myProcess->start(program,arguments); ?

    AlvaroSA 1 Reply Last reply
    1
    • mrjjM mrjj

      @AlvaroS

      " This is the default return value of error()."

      You do call it AFTER u call
      myProcess->start(program,arguments); ?

      AlvaroSA Offline
      AlvaroSA Offline
      AlvaroS
      wrote on last edited by
      #27

      @mrjj Yes:

          myProcess->start(program, arguments);
      
          QProcess::ProcessError error = myProcess->error();
      
      mrjjM 1 Reply Last reply
      0
      • AlvaroSA AlvaroS

        @mrjj Yes:

            myProcess->start(program, arguments);
        
            QProcess::ProcessError error = myProcess->error();
        
        mrjjM Offline
        mrjjM Offline
        mrjj
        Lifetime Qt Champion
        wrote on last edited by
        #28

        @AlvaroS
        hmm really odd then
        it should say FailedToStart

        Just to be 100% clear.

        princi is never run ?

        AlvaroSA 1 Reply Last reply
        1
        • mrjjM mrjj

          @AlvaroS
          hmm really odd then
          it should say FailedToStart

          Just to be 100% clear.

          princi is never run ?

          AlvaroSA Offline
          AlvaroSA Offline
          AlvaroS
          wrote on last edited by
          #29

          @mrjj said:

          @AlvaroS
          hmm really odd then
          it should say FailedToStart

          Just to be 100% clear.

          princi is never run ?

          okey look.
          if I write:

              myProcess->start(program, arguments);
          
              myProcess->waitForFinished(3000);
          
              QProcess::ProcessError error = myProcess->error();
          
          

          Now error says:
          QProcess::Crashed The process crashed some time after starting successfully.

          1 Reply Last reply
          0
          • mrjjM Offline
            mrjjM Offline
            mrjj
            Lifetime Qt Champion
            wrote on last edited by mrjj
            #30

            so it sounds like your princi do run but it crashes?

            oh. sorry my bad. start is async so calling error right after was
            not correct.

            waitForFinished fixed that.

            AlvaroSA 1 Reply Last reply
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            • mrjjM mrjj

              so it sounds like your princi do run but it crashes?

              oh. sorry my bad. start is async so calling error right after was
              not correct.

              waitForFinished fixed that.

              AlvaroSA Offline
              AlvaroSA Offline
              AlvaroS
              wrote on last edited by
              #31

              @mrjj Yes... I think so...
              How should I pass the arguments?

              the arguments of princi are:

              0 wps.front().x() wps.front().y() 0 wps.back().x() wps.front().y() prueba_princi.bmp 0 0 +
              

              so my QStringList arguments is:

               QStringList arguments;
              arguments << "0" << QString::number(wps.front().x()) << QString::number(wps.front().y()) << "0" << QString::number(wps.back().x()) << QString::number(wps.back().y()) << "prueba_princi.bmp" << "0" << "0" << "+" ;
              
              
              1 Reply Last reply
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              • mrjjM Offline
                mrjjM Offline
                mrjj
                Lifetime Qt Champion
                wrote on last edited by
                #32

                it seems fine
                You should look inside princi for how it
                reads it. it must be that part that is crashing ?

                AlvaroSA 2 Replies Last reply
                0
                • mrjjM mrjj

                  it seems fine
                  You should look inside princi for how it
                  reads it. it must be that part that is crashing ?

                  AlvaroSA Offline
                  AlvaroSA Offline
                  AlvaroS
                  wrote on last edited by
                  #33

                  @mrjj yes, but it really rare that if I run from terminal princi runs good...

                  1 Reply Last reply
                  0
                  • mrjjM mrjj

                    it seems fine
                    You should look inside princi for how it
                    reads it. it must be that part that is crashing ?

                    AlvaroSA Offline
                    AlvaroSA Offline
                    AlvaroS
                    wrote on last edited by AlvaroS
                    #34

                    @mrjj And if I write:

                    system ("./princi 0 5 10 0 7 8 prueba_princi.bmp 0 0 +")
                    where 5,10,7 and 8 are wps.front,wps.back....
                    it runs well...

                    mrjjM 1 Reply Last reply
                    0
                    • SGaistS Offline
                      SGaistS Offline
                      SGaist
                      Lifetime Qt Champion
                      wrote on last edited by
                      #35

                      What is that + sign doing as parameter ?

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

                      AlvaroSA 1 Reply Last reply
                      1
                      • SGaistS SGaist

                        What is that + sign doing as parameter ?

                        AlvaroSA Offline
                        AlvaroSA Offline
                        AlvaroS
                        wrote on last edited by
                        #36

                        @SGaist + is just and argument that i have to pass to princi

                        1 Reply Last reply
                        0
                        • AlvaroSA AlvaroS

                          @mrjj And if I write:

                          system ("./princi 0 5 10 0 7 8 prueba_princi.bmp 0 0 +")
                          where 5,10,7 and 8 are wps.front,wps.back....
                          it runs well...

                          mrjjM Offline
                          mrjjM Offline
                          mrjj
                          Lifetime Qt Champion
                          wrote on last edited by
                          #37

                          @AlvaroS
                          well you must debug it then.
                          Try to qDebug inside princi what you read and compare that to what u read for
                          system ("./princi 0 5 10 0 7 8 prueba_princi.bmp 0 0 +")

                          Sadly We cannot guess why you crash from the code shown.

                          Also you dump the arguments to qDebug before u
                          call start, just to see what u are sending also.

                          and then take it from there.

                          1 Reply Last reply
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