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Extract Number from an Alphanumeric QString

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  • S Shahmisufi

    I have a QString of "s150 d300". How can I get the numbers from the QString and convert it into integer. Simply using 'toInt' is not working.

    Let say, from the QString of "s150 d300", only the number after the alphabet 'd' is meaningful to me. How can I extract the value of '300' from the string?

    Thank you very much for your time.

    raven-worxR Offline
    raven-worxR Offline
    raven-worx
    Moderators
    wrote on last edited by raven-worx
    #2

    @Shahmisufi

    QRegularExpression rx("[0-9]+");
    QRegularExpressionMatch match = rx.match("s150 d300");
    if ( match.hasMatch()  ) 
    {
        QString matched1 = match.captured(0); // matched == "150"
        QString matched2 = match.captured(1); // matched == "300"
    }
    

    if you really just want the number after the "d" only use this:

    QRegularExpression rx("d([0-9]+)");
    QRegularExpressionMatch match = rx.match("s150 d300");
    if ( match.hasMatch()  ) 
    {
        QString matched1 = match.captured(0); // matched == "300"
    }
    

    (untested)

    --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
    If you have a question please use the forum so others can benefit from the solution in the future

    VRoninV S 2 Replies Last reply
    3
    • S Shahmisufi

      I have a QString of "s150 d300". How can I get the numbers from the QString and convert it into integer. Simply using 'toInt' is not working.

      Let say, from the QString of "s150 d300", only the number after the alphabet 'd' is meaningful to me. How can I extract the value of '300' from the string?

      Thank you very much for your time.

      m.sueM Offline
      m.sueM Offline
      m.sue
      wrote on last edited by m.sue
      #3

      Hi @Shahmisufi

      QString szStr="s150 d300";
      QRegExp regExp(qa(".*d(\\d*)"),Qt::CaseSensitive,QRegExp::RegExp);	//non-greedy wildcards
      if (regExp.indexIn(szStr) > 0) {
      	QString szNumber=regExp.cap(1);
      	//do something
      }
      

      -Michael

      raven-worxR 1 Reply Last reply
      0
      • m.sueM m.sue

        Hi @Shahmisufi

        QString szStr="s150 d300";
        QRegExp regExp(qa(".*d(\\d*)"),Qt::CaseSensitive,QRegExp::RegExp);	//non-greedy wildcards
        if (regExp.indexIn(szStr) > 0) {
        	QString szNumber=regExp.cap(1);
        	//do something
        }
        

        -Michael

        raven-worxR Offline
        raven-worxR Offline
        raven-worx
        Moderators
        wrote on last edited by
        #4

        @m.sue
        just to note:
        QRegExp is deprecated since Qt5. QRegularExpression should be used instead.

        --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
        If you have a question please use the forum so others can benefit from the solution in the future

        1 Reply Last reply
        2
        • raven-worxR raven-worx

          @Shahmisufi

          QRegularExpression rx("[0-9]+");
          QRegularExpressionMatch match = rx.match("s150 d300");
          if ( match.hasMatch()  ) 
          {
              QString matched1 = match.captured(0); // matched == "150"
              QString matched2 = match.captured(1); // matched == "300"
          }
          

          if you really just want the number after the "d" only use this:

          QRegularExpression rx("d([0-9]+)");
          QRegularExpressionMatch match = rx.match("s150 d300");
          if ( match.hasMatch()  ) 
          {
              QString matched1 = match.captured(0); // matched == "300"
          }
          

          (untested)

          VRoninV Offline
          VRoninV Offline
          VRonin
          wrote on last edited by
          #5

          @raven-worx

          \\\\d

          why the 4(i.e. 2) slashes? shouldn't it just be "d(\\d+)" ?

          Anticipating the questions: \d is the same as [0-9]

          "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
          ~Napoleon Bonaparte

          On a crusade to banish setIndexWidget() from the holy land of Qt

          raven-worxR 1 Reply Last reply
          2
          • VRoninV VRonin

            @raven-worx

            \\\\d

            why the 4(i.e. 2) slashes? shouldn't it just be "d(\\d+)" ?

            Anticipating the questions: \d is the same as [0-9]

            raven-worxR Offline
            raven-worxR Offline
            raven-worx
            Moderators
            wrote on last edited by
            #6

            @VRonin
            I wanted to make clear that \d isn't related to the "d" in the string so i used [0-9].
            You are right, in the second example i was thinking too complicated. Updated my post.

            --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
            If you have a question please use the forum so others can benefit from the solution in the future

            1 Reply Last reply
            0
            • SeenuS Offline
              SeenuS Offline
              Seenu
              wrote on last edited by
              #7

              @Shahmisufi ,

              You given string example "s150 d300" and in real case string can be anything. According to me your requirement is last occurrence number you required from input string. Below added works for all scenario's.

              pass any string to below function , output will be last occurance number

              this->lastoccurancenumber("s150d300");
              void lastoccurancenumber(QString str)
              {

              int final_number;
              QString s = str;
              QString s1="";
              for(int i = s.length()-1;i>=0;i--)
              {
                  QString temp = s[i];
                  QByteArray ba = temp.toLatin1();
                  char *c_str2 = ba.data();
                  char c_temp = c_str2[0];
                  if(!isalpha(c_temp))
                  {
                      qDebug()<<"string"<<s[i]<<"nu,ber is"<<temp<<endl;
                      s1.append(temp);
                      qDebug()<<"charater is"<<s1<<endl;
                  }
                  else
                  {
                      break;
                  }
              }
              
              std::reverse(s1.begin(), s1.end());
              final_number = s1.toInt();
              qDebug()<<"charater is"<<final_number<<endl;
              

              }

              raven-worxR 1 Reply Last reply
              2
              • SeenuS Seenu

                @Shahmisufi ,

                You given string example "s150 d300" and in real case string can be anything. According to me your requirement is last occurrence number you required from input string. Below added works for all scenario's.

                pass any string to below function , output will be last occurance number

                this->lastoccurancenumber("s150d300");
                void lastoccurancenumber(QString str)
                {

                int final_number;
                QString s = str;
                QString s1="";
                for(int i = s.length()-1;i>=0;i--)
                {
                    QString temp = s[i];
                    QByteArray ba = temp.toLatin1();
                    char *c_str2 = ba.data();
                    char c_temp = c_str2[0];
                    if(!isalpha(c_temp))
                    {
                        qDebug()<<"string"<<s[i]<<"nu,ber is"<<temp<<endl;
                        s1.append(temp);
                        qDebug()<<"charater is"<<s1<<endl;
                    }
                    else
                    {
                        break;
                    }
                }
                
                std::reverse(s1.begin(), s1.end());
                final_number = s1.toInt();
                qDebug()<<"charater is"<<final_number<<endl;
                

                }

                raven-worxR Offline
                raven-worxR Offline
                raven-worx
                Moderators
                wrote on last edited by
                #8

                @Seenu
                Motto: why easy when u can do it complicated

                --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
                If you have a question please use the forum so others can benefit from the solution in the future

                1 Reply Last reply
                0
                • raven-worxR raven-worx

                  @Shahmisufi

                  QRegularExpression rx("[0-9]+");
                  QRegularExpressionMatch match = rx.match("s150 d300");
                  if ( match.hasMatch()  ) 
                  {
                      QString matched1 = match.captured(0); // matched == "150"
                      QString matched2 = match.captured(1); // matched == "300"
                  }
                  

                  if you really just want the number after the "d" only use this:

                  QRegularExpression rx("d([0-9]+)");
                  QRegularExpressionMatch match = rx.match("s150 d300");
                  if ( match.hasMatch()  ) 
                  {
                      QString matched1 = match.captured(0); // matched == "300"
                  }
                  

                  (untested)

                  S Offline
                  S Offline
                  Shahmisufi
                  wrote on last edited by
                  #9

                  @raven-worx I have tested the code and it returns "d300" instead of "300"

                  jsulmJ 1 Reply Last reply
                  0
                  • SeenuS Offline
                    SeenuS Offline
                    Seenu
                    wrote on last edited by
                    #10

                    @Shahmisufi

                    Try the code once which i posted ....

                    1 Reply Last reply
                    2
                    • S Shahmisufi

                      @raven-worx I have tested the code and it returns "d300" instead of "300"

                      jsulmJ Offline
                      jsulmJ Offline
                      jsulm
                      Lifetime Qt Champion
                      wrote on last edited by jsulm
                      #11

                      @Shahmisufi This works for me:

                      QRegularExpression rx("[0-9]+");
                      QRegularExpressionMatchIterator matches = rx.globalMatch("s150 d300");
                      while (matches.hasNext()) {
                          QRegularExpressionMatch match = matches.next();
                          qDebug() << match.captured(0);
                      }
                      

                      @Seenu your solution might work (I didn't test it) but it is much more complex compared to a solution using a simple regular expression.

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

                      1 Reply Last reply
                      2
                      • SeenuS Offline
                        SeenuS Offline
                        Seenu
                        wrote on last edited by
                        #12

                        @jsulm

                        Ya its complex , but it will return last occurrence number in a string and is in generic format

                        jsulmJ 1 Reply Last reply
                        2
                        • SeenuS Seenu

                          @jsulm

                          Ya its complex , but it will return last occurrence number in a string and is in generic format

                          jsulmJ Offline
                          jsulmJ Offline
                          jsulm
                          Lifetime Qt Champion
                          wrote on last edited by
                          #13

                          @Seenu What do you mean by "generic format"?
                          You can do the same with a simple regular expression.

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

                          1 Reply Last reply
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