Change only a specific Default Parameter on a function

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13















I'm using qt and I am trying to use the QInputDialog::getText() function to get input from the user, from the Documentation the definition of the function is:



QString QInputDialog::getText(QWidget * parent, const QString & title, const QString & label, QLineEdit::EchoMode mode = QLineEdit::Normal, const QString & text = QString(), bool * ok = 0, Qt::WindowFlags flags = 0, Qt::InputMethodHints inputMethodHints = Qt::ImhNone)


and here is my code:



bool ok=0;
newAddress = QInputDialog::getText(0,"Enter an Address to Validate",
"Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)"
,&ok);


but I get the Error:



error: no matching function for call to 'QInputDialog::getText(int, const char [29], const char [80], bool*)'
,&ok);
^


but when I pass in all the arguments before the *ok argument like:



bool ok=0;
newAddress = QInputDialog::getText(0,"Enter an Address to Validate",
"Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)"
,QLineEdit::Normal,
QString(),&ok);


it works.



I really don't understand why cant I just change the default parameter I want and leave the rest as default?.










share|improve this question




























    13















    I'm using qt and I am trying to use the QInputDialog::getText() function to get input from the user, from the Documentation the definition of the function is:



    QString QInputDialog::getText(QWidget * parent, const QString & title, const QString & label, QLineEdit::EchoMode mode = QLineEdit::Normal, const QString & text = QString(), bool * ok = 0, Qt::WindowFlags flags = 0, Qt::InputMethodHints inputMethodHints = Qt::ImhNone)


    and here is my code:



    bool ok=0;
    newAddress = QInputDialog::getText(0,"Enter an Address to Validate",
    "Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)"
    ,&ok);


    but I get the Error:



    error: no matching function for call to 'QInputDialog::getText(int, const char [29], const char [80], bool*)'
    ,&ok);
    ^


    but when I pass in all the arguments before the *ok argument like:



    bool ok=0;
    newAddress = QInputDialog::getText(0,"Enter an Address to Validate",
    "Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)"
    ,QLineEdit::Normal,
    QString(),&ok);


    it works.



    I really don't understand why cant I just change the default parameter I want and leave the rest as default?.










    share|improve this question


























      13












      13








      13








      I'm using qt and I am trying to use the QInputDialog::getText() function to get input from the user, from the Documentation the definition of the function is:



      QString QInputDialog::getText(QWidget * parent, const QString & title, const QString & label, QLineEdit::EchoMode mode = QLineEdit::Normal, const QString & text = QString(), bool * ok = 0, Qt::WindowFlags flags = 0, Qt::InputMethodHints inputMethodHints = Qt::ImhNone)


      and here is my code:



      bool ok=0;
      newAddress = QInputDialog::getText(0,"Enter an Address to Validate",
      "Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)"
      ,&ok);


      but I get the Error:



      error: no matching function for call to 'QInputDialog::getText(int, const char [29], const char [80], bool*)'
      ,&ok);
      ^


      but when I pass in all the arguments before the *ok argument like:



      bool ok=0;
      newAddress = QInputDialog::getText(0,"Enter an Address to Validate",
      "Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)"
      ,QLineEdit::Normal,
      QString(),&ok);


      it works.



      I really don't understand why cant I just change the default parameter I want and leave the rest as default?.










      share|improve this question
















      I'm using qt and I am trying to use the QInputDialog::getText() function to get input from the user, from the Documentation the definition of the function is:



      QString QInputDialog::getText(QWidget * parent, const QString & title, const QString & label, QLineEdit::EchoMode mode = QLineEdit::Normal, const QString & text = QString(), bool * ok = 0, Qt::WindowFlags flags = 0, Qt::InputMethodHints inputMethodHints = Qt::ImhNone)


      and here is my code:



      bool ok=0;
      newAddress = QInputDialog::getText(0,"Enter an Address to Validate",
      "Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)"
      ,&ok);


      but I get the Error:



      error: no matching function for call to 'QInputDialog::getText(int, const char [29], const char [80], bool*)'
      ,&ok);
      ^


      but when I pass in all the arguments before the *ok argument like:



      bool ok=0;
      newAddress = QInputDialog::getText(0,"Enter an Address to Validate",
      "Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)"
      ,QLineEdit::Normal,
      QString(),&ok);


      it works.



      I really don't understand why cant I just change the default parameter I want and leave the rest as default?.







      c++ qt qt5






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Mar 6 at 16:03







      Makhele Sabata

















      asked Mar 6 at 9:52









      Makhele SabataMakhele Sabata

      10917




      10917






















          3 Answers
          3






          active

          oldest

          votes


















          14














          When you pass a value for a particular parameter that has a default argument, you have to pass values for all the default parameters before it. Otherwise, the value you have passed will be taken as the value for the first default parameter.



          So you have to do this:



          newAddress = QInputDialog::getText(
          0,
          "Enter an Address to Validate",
          "Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)",
          QLineEdit::Normal,
          QString(),
          &ok);


          You can leave out passing values for the parameters after bool * parameter.



          The C++ standard states in [dcl.fct.default]/1




          Default arguments will be used in calls where trailing arguments are missing.







          share|improve this answer

























          • I worked with Python when i started learning programming, and it i had this functionality where you could pass the arguments by name. it would be nice if they had something like that in C++. Thanks for the answer I wasn't aware of the trailing arguments issue.

            – Makhele Sabata
            Mar 6 at 13:15












          • You are welcome.

            – P.W
            Mar 6 at 13:33


















          8














          In C++ you can only use (one or multiple) default parameters at the end of the parameter list. If you omit parameters in the middle, the compiler has no way of knowing, which argument belongs to which parameter. Therefore you have to specify the default parameters QLineEdit::Normal and QString() manually before passing &ok.



          In your not working case the compiler tries to match your bool pointer to the next type in the parameter list, which is QLineEdit::EchoMode and therefore not compatible.






          share|improve this answer






























            3














            the error is beacuse of the optional paramteres:



            QString QInputDialog::getText(
            QWidget * parent,
            const QString & title,
            const QString & label,
            QLineEdit::EchoMode mode = QLineEdit::Normal,
            const QString& text = QString(),
            bool * ok = 0,
            Qt::WindowFlags flags = 0,
            Qt::InputMethodHints inputMethodHints = Qt::ImhNone)


            QInputDialog::getText(
            0,
            "Enter an Address to Validate",
            "Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)",
            --> QLineEdit::EchoMode ??
            --> QString& text ??
            &ok);


            if you set one optional parameter, you have to set all the optional paramteters to the left of that, in your case QLineEdit::EchoMode and QString& text






            share|improve this answer























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              3 Answers
              3






              active

              oldest

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              3 Answers
              3






              active

              oldest

              votes









              active

              oldest

              votes






              active

              oldest

              votes









              14














              When you pass a value for a particular parameter that has a default argument, you have to pass values for all the default parameters before it. Otherwise, the value you have passed will be taken as the value for the first default parameter.



              So you have to do this:



              newAddress = QInputDialog::getText(
              0,
              "Enter an Address to Validate",
              "Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)",
              QLineEdit::Normal,
              QString(),
              &ok);


              You can leave out passing values for the parameters after bool * parameter.



              The C++ standard states in [dcl.fct.default]/1




              Default arguments will be used in calls where trailing arguments are missing.







              share|improve this answer

























              • I worked with Python when i started learning programming, and it i had this functionality where you could pass the arguments by name. it would be nice if they had something like that in C++. Thanks for the answer I wasn't aware of the trailing arguments issue.

                – Makhele Sabata
                Mar 6 at 13:15












              • You are welcome.

                – P.W
                Mar 6 at 13:33















              14














              When you pass a value for a particular parameter that has a default argument, you have to pass values for all the default parameters before it. Otherwise, the value you have passed will be taken as the value for the first default parameter.



              So you have to do this:



              newAddress = QInputDialog::getText(
              0,
              "Enter an Address to Validate",
              "Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)",
              QLineEdit::Normal,
              QString(),
              &ok);


              You can leave out passing values for the parameters after bool * parameter.



              The C++ standard states in [dcl.fct.default]/1




              Default arguments will be used in calls where trailing arguments are missing.







              share|improve this answer

























              • I worked with Python when i started learning programming, and it i had this functionality where you could pass the arguments by name. it would be nice if they had something like that in C++. Thanks for the answer I wasn't aware of the trailing arguments issue.

                – Makhele Sabata
                Mar 6 at 13:15












              • You are welcome.

                – P.W
                Mar 6 at 13:33













              14












              14








              14







              When you pass a value for a particular parameter that has a default argument, you have to pass values for all the default parameters before it. Otherwise, the value you have passed will be taken as the value for the first default parameter.



              So you have to do this:



              newAddress = QInputDialog::getText(
              0,
              "Enter an Address to Validate",
              "Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)",
              QLineEdit::Normal,
              QString(),
              &ok);


              You can leave out passing values for the parameters after bool * parameter.



              The C++ standard states in [dcl.fct.default]/1




              Default arguments will be used in calls where trailing arguments are missing.







              share|improve this answer















              When you pass a value for a particular parameter that has a default argument, you have to pass values for all the default parameters before it. Otherwise, the value you have passed will be taken as the value for the first default parameter.



              So you have to do this:



              newAddress = QInputDialog::getText(
              0,
              "Enter an Address to Validate",
              "Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)",
              QLineEdit::Normal,
              QString(),
              &ok);


              You can leave out passing values for the parameters after bool * parameter.



              The C++ standard states in [dcl.fct.default]/1




              Default arguments will be used in calls where trailing arguments are missing.








              share|improve this answer














              share|improve this answer



              share|improve this answer








              edited Mar 6 at 11:55

























              answered Mar 6 at 10:11









              P.WP.W

              18k41657




              18k41657












              • I worked with Python when i started learning programming, and it i had this functionality where you could pass the arguments by name. it would be nice if they had something like that in C++. Thanks for the answer I wasn't aware of the trailing arguments issue.

                – Makhele Sabata
                Mar 6 at 13:15












              • You are welcome.

                – P.W
                Mar 6 at 13:33

















              • I worked with Python when i started learning programming, and it i had this functionality where you could pass the arguments by name. it would be nice if they had something like that in C++. Thanks for the answer I wasn't aware of the trailing arguments issue.

                – Makhele Sabata
                Mar 6 at 13:15












              • You are welcome.

                – P.W
                Mar 6 at 13:33
















              I worked with Python when i started learning programming, and it i had this functionality where you could pass the arguments by name. it would be nice if they had something like that in C++. Thanks for the answer I wasn't aware of the trailing arguments issue.

              – Makhele Sabata
              Mar 6 at 13:15






              I worked with Python when i started learning programming, and it i had this functionality where you could pass the arguments by name. it would be nice if they had something like that in C++. Thanks for the answer I wasn't aware of the trailing arguments issue.

              – Makhele Sabata
              Mar 6 at 13:15














              You are welcome.

              – P.W
              Mar 6 at 13:33





              You are welcome.

              – P.W
              Mar 6 at 13:33













              8














              In C++ you can only use (one or multiple) default parameters at the end of the parameter list. If you omit parameters in the middle, the compiler has no way of knowing, which argument belongs to which parameter. Therefore you have to specify the default parameters QLineEdit::Normal and QString() manually before passing &ok.



              In your not working case the compiler tries to match your bool pointer to the next type in the parameter list, which is QLineEdit::EchoMode and therefore not compatible.






              share|improve this answer



























                8














                In C++ you can only use (one or multiple) default parameters at the end of the parameter list. If you omit parameters in the middle, the compiler has no way of knowing, which argument belongs to which parameter. Therefore you have to specify the default parameters QLineEdit::Normal and QString() manually before passing &ok.



                In your not working case the compiler tries to match your bool pointer to the next type in the parameter list, which is QLineEdit::EchoMode and therefore not compatible.






                share|improve this answer

























                  8












                  8








                  8







                  In C++ you can only use (one or multiple) default parameters at the end of the parameter list. If you omit parameters in the middle, the compiler has no way of knowing, which argument belongs to which parameter. Therefore you have to specify the default parameters QLineEdit::Normal and QString() manually before passing &ok.



                  In your not working case the compiler tries to match your bool pointer to the next type in the parameter list, which is QLineEdit::EchoMode and therefore not compatible.






                  share|improve this answer













                  In C++ you can only use (one or multiple) default parameters at the end of the parameter list. If you omit parameters in the middle, the compiler has no way of knowing, which argument belongs to which parameter. Therefore you have to specify the default parameters QLineEdit::Normal and QString() manually before passing &ok.



                  In your not working case the compiler tries to match your bool pointer to the next type in the parameter list, which is QLineEdit::EchoMode and therefore not compatible.







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered Mar 6 at 10:08









                  AlbertMAlbertM

                  524418




                  524418





















                      3














                      the error is beacuse of the optional paramteres:



                      QString QInputDialog::getText(
                      QWidget * parent,
                      const QString & title,
                      const QString & label,
                      QLineEdit::EchoMode mode = QLineEdit::Normal,
                      const QString& text = QString(),
                      bool * ok = 0,
                      Qt::WindowFlags flags = 0,
                      Qt::InputMethodHints inputMethodHints = Qt::ImhNone)


                      QInputDialog::getText(
                      0,
                      "Enter an Address to Validate",
                      "Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)",
                      --> QLineEdit::EchoMode ??
                      --> QString& text ??
                      &ok);


                      if you set one optional parameter, you have to set all the optional paramteters to the left of that, in your case QLineEdit::EchoMode and QString& text






                      share|improve this answer



























                        3














                        the error is beacuse of the optional paramteres:



                        QString QInputDialog::getText(
                        QWidget * parent,
                        const QString & title,
                        const QString & label,
                        QLineEdit::EchoMode mode = QLineEdit::Normal,
                        const QString& text = QString(),
                        bool * ok = 0,
                        Qt::WindowFlags flags = 0,
                        Qt::InputMethodHints inputMethodHints = Qt::ImhNone)


                        QInputDialog::getText(
                        0,
                        "Enter an Address to Validate",
                        "Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)",
                        --> QLineEdit::EchoMode ??
                        --> QString& text ??
                        &ok);


                        if you set one optional parameter, you have to set all the optional paramteters to the left of that, in your case QLineEdit::EchoMode and QString& text






                        share|improve this answer

























                          3












                          3








                          3







                          the error is beacuse of the optional paramteres:



                          QString QInputDialog::getText(
                          QWidget * parent,
                          const QString & title,
                          const QString & label,
                          QLineEdit::EchoMode mode = QLineEdit::Normal,
                          const QString& text = QString(),
                          bool * ok = 0,
                          Qt::WindowFlags flags = 0,
                          Qt::InputMethodHints inputMethodHints = Qt::ImhNone)


                          QInputDialog::getText(
                          0,
                          "Enter an Address to Validate",
                          "Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)",
                          --> QLineEdit::EchoMode ??
                          --> QString& text ??
                          &ok);


                          if you set one optional parameter, you have to set all the optional paramteters to the left of that, in your case QLineEdit::EchoMode and QString& text






                          share|improve this answer













                          the error is beacuse of the optional paramteres:



                          QString QInputDialog::getText(
                          QWidget * parent,
                          const QString & title,
                          const QString & label,
                          QLineEdit::EchoMode mode = QLineEdit::Normal,
                          const QString& text = QString(),
                          bool * ok = 0,
                          Qt::WindowFlags flags = 0,
                          Qt::InputMethodHints inputMethodHints = Qt::ImhNone)


                          QInputDialog::getText(
                          0,
                          "Enter an Address to Validate",
                          "Adress: comma separated (e.g Address line 1, Address line 2, City, Postal Code)",
                          --> QLineEdit::EchoMode ??
                          --> QString& text ??
                          &ok);


                          if you set one optional parameter, you have to set all the optional paramteters to the left of that, in your case QLineEdit::EchoMode and QString& text







                          share|improve this answer












                          share|improve this answer



                          share|improve this answer










                          answered Mar 6 at 10:24









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