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    Forum Updated on Feb 6th

    Solved copy from QStringList to QString

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    • K-Str
      K-Str last edited by K-Str

      Hi,
      since some days I try to copy one element of a QStrinList to a QList value.

      QTS = QTSL[0];
      

      Where

      • QTS is a simple QTString
      • list itemQTSL[0] is an element of QTStringList

      But in this way it doesn't work.
      I get an error:
      The inferior stopped because it received a signal from the operating system.

      Signal name :
      SIGSEGV
      Signal meaning :
      Segmentation fault

      I think a solution is quiete simple.
      Please could someone help me?
      Thanks!

      1 Reply Last reply Reply Quote 0
      • K
        khryleption last edited by

        Hi,
        Maybe your list is empty, do you check the list size ?

        1 Reply Last reply Reply Quote 1
        • K-Str
          K-Str last edited by

          Hi khryleption ,
          thanks for your answer.
          The list is not empty and in the elemnt QTSL[0] are also some data.
          qDebug << QTSL[0] shows the expected content.

          1 Reply Last reply Reply Quote 0
          • K-Str
            K-Str last edited by

            Hi,
            is it possible that the QString item QTS in uninitialized.
            If yes how can I solve this?

            Pablo J. Rogina 1 Reply Last reply Reply Quote 0
            • Pablo J. Rogina
              Pablo J. Rogina @K-Str last edited by

              @K-Str said in copy from QStringList to QString:

              is it possible that the QString item QTS in uninitialized.

              could you please show a more complete code snippet of what you have so far?

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              1 Reply Last reply Reply Quote 2
              • K-Str
                K-Str last edited by K-Str

                @Pablo-J-Rogina said in copy from QStringList to QString:

                could you please show a more complete code snippet of what you have so far?

                Hi Pablo J. Rogina,
                thanks for your answer,
                I think there is something wrong by using memset .

                void ClassSqlite::conv_tm_to_time_t()
                {
                    char buffer1[80];
                    QString qs;
                    time_t rawtime_akt, rawtime_neu;
                    struct tm * timeinfo_akt, timeinfo_neu;
                    qDebug() << CSVliste.size();
                    qDebug() << qs.size();
                    qs = CSVliste[0];
                    memset (&timeinfo_akt, 0, sizeof(struct tm));  <<<==== this statement overwites qs
                    time (&rawtime_akt);
                    timeinfo_akt = localtime (&rawtime_akt);
                    strftime (buffer1,80,"%H:%M:%S",timeinfo_akt);
                    Uhrzeit = buffer1;
                    strftime (buffer1,80,"%e.%m.%Y", timeinfo_akt);
                    Datum = buffer1;
                    memset (&timeinfo_neu, 0, sizeof(struct tm));
                    strptime(qs.toStdString().c_str(), "%d-%m-%Y %H:%M:%S", &timeinfo_neu);
                //    rawtime_neu=mktime(&timeinfo_neu);
                //    qDebug() << "Der unteschied ist: " << (float)rawtime_akt-(float)rawtime_neu;
                }
                

                Is there a way around tihs?

                JonB 1 Reply Last reply Reply Quote 0
                • JonB
                  JonB @K-Str last edited by JonB

                  @K-Str said in copy from QStringList to QString:

                  struct tm * timeinfo_akt, timeinfo_neu;
                  
                  memset (&timeinfo_akt, 0, sizeof(struct tm));  <<<==== this statement overwites qs
                  

                  timeinfo_akt is just a pointer-size. This overwrites the stack. You meant

                  struct tm timeinfo_akt, timeinfo_neu;
                  

                  You should not be using any of this code in Qt/nowadays. Seriously.

                  1 Reply Last reply Reply Quote 4
                  • SGaist
                    SGaist Lifetime Qt Champion last edited by

                    Hi,

                    Would it not be simpler to use QDateTime ?

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

                    1 Reply Last reply Reply Quote 2
                    • K-Str
                      K-Str last edited by K-Str

                      Hi SGaist,
                      thanks for your answer.
                      I tried to use QDAteTime in the following way:

                      #include <QCoreApplication>
                      #include <QDebug>
                      #include <QString>
                      #include <QDateTime>
                      
                      #include <string>
                      
                      using namespace std;
                      
                      bool TimeCheck()
                      {
                          QString QS_OldTime = "2020-08-20 09:48:33";
                          QString QS_Format = "yyyy-MM-dd hh:mm.ss";
                          QDateTime QD_OldTime, QD_AktTime;
                          QD_AktTime = QDateTime::currentDateTime();
                          QD_OldTime = QDateTime::fromString(QS_OldTime, QS_Format);
                          return true;
                      }
                      
                      
                      int main(int argc, char *argv[])
                      {
                          QCoreApplication a(argc, argv);
                          if (TimeCheck())
                          {
                              qDebug() << "OK";
                          }
                          else
                          {
                              qDebug() << "NOK";
                          }
                          return a.exec();
                      }
                      
                      
                      

                      This little code should be used to check the difference betweem the aktual time and the old time
                      But i'm quiete confused because I do not get the expected results:

                      • The values the values for
                        actual date and time : QDateTime(2020-08-20 12:19:19.182 CEST Qt::TimeSpec(LocalTime))
                        Old date and time : QDateTime( Qt::TimeSpec(LocalTime))

                      • How can I get values where I can check easily how the difference is in seconds.

                      Whats wrong with the statement

                      QD_OldTime = QDateTime::fromString(QS_OldTime, QS_Format);
                      
                      J.Hilk 1 Reply Last reply Reply Quote 0
                      • J.Hilk
                        J.Hilk Moderators @K-Str last edited by

                        @K-Str
                        do you spot the difference in format to actual text?

                        09:48:33
                        hh:mm.ss

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                        Q: What does it do?
                        A: It turns blue.

                        1 Reply Last reply Reply Quote 3
                        • K-Str
                          K-Str last edited by K-Str

                          hi J.Hilk.
                          thanks for your answer!
                          yes but it would be better to have it in seconds like 900 seconds for 15 minutes.

                          J.Hilk 1 Reply Last reply Reply Quote 0
                          • J.Hilk
                            J.Hilk Moderators @K-Str last edited by

                            @K-Str what do you want in seconds, from what starting point/time

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

                            Qt Needs YOUR vote: https://bugreports.qt.io/browse/QTQAINFRA-4121


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

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                            • K-Str
                              K-Str last edited by

                              Hi j.Hilk,
                              If it is possibel to get something like from time_t mode.

                              J.Hilk 1 Reply Last reply Reply Quote 0
                              • J.Hilk
                                J.Hilk Moderators @K-Str last edited by

                                @K-Str
                                https://doc.qt.io/qt-5/qdatetime.html#toSecsSinceEpoch

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

                                Qt Needs YOUR vote: https://bugreports.qt.io/browse/QTQAINFRA-4121


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

                                1 Reply Last reply Reply Quote 1
                                • K-Str
                                  K-Str last edited by K-Str

                                  J.Hilk,
                                  thanks a lot for this tip.
                                  It works perfect.
                                  But how can I get the milliseconds since a given time like

                                      QString QS_OldTime = "2020-08-20 09:48:33";
                                  

                                  This staement

                                      QD_OldTime = QDateTime::fromString(QS_OldTime, QS_Format);
                                  

                                  doesn't work correctly

                                  J.Hilk 1 Reply Last reply Reply Quote 0
                                  • J.Hilk
                                    J.Hilk Moderators @K-Str last edited by

                                    @K-Str

                                    This statement
                                    QD_OldTime = QDateTime::fromString(QS_OldTime, QS_Format);
                                    doesn't work correctly

                                    it doesn't work correctly because your QS_Format is wrong, like I posted previously

                                    But how can I get the milliseconds since a given

                                    https://doc.qt.io/qt-5/qdatetime.html#msecsTo

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

                                    Qt Needs YOUR vote: https://bugreports.qt.io/browse/QTQAINFRA-4121


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

                                    1 Reply Last reply Reply Quote 0
                                    • K-Str
                                      K-Str last edited by K-Str

                                      Hi j.Hilk,
                                      ok the part

                                          QT_Akt=QDateTime::currentMSecsSinceEpoch();
                                      

                                      works perfect!
                                      But what about this part?

                                          QString QS_OldTime = "2020-08-15 09:48:33";
                                          QString QS_Format = "yyyy-MM-dd hh:mm.ss";
                                          QDateTime QD_OldTime, QD_AktTime;
                                          QD_OldTime = QDateTime::fromString(QS_OldTime, QS_Format);
                                      
                                      

                                      I saw the value of QD_OldTime is not correctly assigned
                                      There was a "." in

                                      QString QS_Format = "yyyy-MM-dd hh:mm.ss";
                                      

                                      on the place ":mm.ss"
                                      Now it works perfect.
                                      Thanks a lot!

                                      JonB KroMignon 2 Replies Last reply Reply Quote 0
                                      • JonB
                                        JonB @K-Str last edited by

                                        @K-Str
                                        Just to say: I was the peson who said you should not be using your old C code with memcpy() etc. Your new code with QString, QDateTime looks a lot neater and more C++, well done! :)

                                        1 Reply Last reply Reply Quote 1
                                        • KroMignon
                                          KroMignon @K-Str last edited by

                                          @K-Str said in copy from QStringList to QString:

                                          But what about this part?
                                          QString QS_OldTime = "2020-08-15 09:48:33";
                                          QString QS_Format = "yyyy-MM-dd hh:mm.ss";
                                          QDateTime QD_OldTime, QD_AktTime;
                                          QD_OldTime = QDateTime::fromString(QS_OldTime, QS_Format);

                                          This can NOT work because the pattern are not matching.
                                          You have to change QS_OldTime or QS_Format.
                                          Read carefully and you will see your typo ;)

                                          It is an old maxim of mine that when you have excluded the impossible, whatever remains, however improbable, must be the truth. (Sherlock Holmes)

                                          1 Reply Last reply Reply Quote 1
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