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Exact match in QStringList

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  • U user4592357

    but they search for a substring, i need exact match of a string

    mrjjM Offline
    mrjjM Offline
    mrjj
    Lifetime Qt Champion
    wrote on last edited by
    #4

    @user4592357
    Hi
    A low tech solution could just be

     QStringList list;
      list << "anders" << "peter" << "hanspeter" << "polka" << "hans";
    
      foreach (const QString& var, list) {
        if ( var == "hans" ) qDebug() << "HIT!";
      }
    
    

    But that dont allow for Case sensitive matching.

    U 1 Reply Last reply
    0
    • mrjjM mrjj

      @user4592357
      Hi
      A low tech solution could just be

       QStringList list;
        list << "anders" << "peter" << "hanspeter" << "polka" << "hans";
      
        foreach (const QString& var, list) {
          if ( var == "hans" ) qDebug() << "HIT!";
        }
      
      

      But that dont allow for Case sensitive matching.

      U Offline
      U Offline
      user4592357
      wrote on last edited by
      #5

      @mrjj

      that's what i currently have. i don't care aboit case sensitivity in my problem. but i wanted a more "sophisticated" method, or to be precise, a shorter and already implemented one

      1 Reply Last reply
      0
      • SGaistS Offline
        SGaistS Offline
        SGaist
        Lifetime Qt Champion
        wrote on last edited by
        #6

        There's not even a need for QRegularExpression.

        qDebug() << list.indexOf("cd") << list.indexOf("abcd");
        

        You'll get -1 and 0.

        So you replace your current if condition with list.indexOf(text) == -1 and you're good to go.

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

        JonBJ 1 Reply Last reply
        5
        • SGaistS SGaist

          There's not even a need for QRegularExpression.

          qDebug() << list.indexOf("cd") << list.indexOf("abcd");
          

          You'll get -1 and 0.

          So you replace your current if condition with list.indexOf(text) == -1 and you're good to go.

          JonBJ Offline
          JonBJ Offline
          JonB
          wrote on last edited by
          #7

          @SGaist
          I don't get what you're proposing. Are you saying QStringList::indexOf only finds complete-element matches, not substrings (the docs don't make this clear to me), but the OP used QStringList::contains() and that does not behave same? Plus, docs say that all overloads of QStringList::indexOf take a regular expression type argument, how does list.indexOf("cd") return -1?

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          • SGaistS Offline
            SGaistS Offline
            SGaist
            Lifetime Qt Champion
            wrote on last edited by SGaist
            #8

            indexOf documentation states: "the first exact match" well except the overload for QRegularExpression but that might be a documentation issue.

            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
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            • SGaistS Offline
              SGaistS Offline
              SGaist
              Lifetime Qt Champion
              wrote on last edited by
              #9

              It's indeed a documentation issue. It works as the other overload.

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

              JonBJ 1 Reply Last reply
              0
              • U Offline
                U Offline
                user4592357
                wrote on last edited by
                #10

                that is why i was confused by looking at the docs. sorry, anyways.
                indexOf() does what i was looking for

                1 Reply Last reply
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                • SGaistS SGaist

                  It's indeed a documentation issue. It works as the other overload.

                  JonBJ Offline
                  JonBJ Offline
                  JonB
                  wrote on last edited by
                  #11

                  @SGaist
                  So indexOf, which only accepts a regular expression, does a ^pattern$ ("exact" match?) against each element, and contains does a sub string (across all elements concatenated or each element individually?) ?

                  U 1 Reply Last reply
                  0
                  • JonBJ JonB

                    @SGaist
                    So indexOf, which only accepts a regular expression, does a ^pattern$ ("exact" match?) against each element, and contains does a sub string (across all elements concatenated or each element individually?) ?

                    U Offline
                    U Offline
                    user4592357
                    wrote on last edited by
                    #12

                    @JNBarchan

                    that's what my experience was

                    1 Reply Last reply
                    1
                    • SGaistS Offline
                      SGaistS Offline
                      SGaist
                      Lifetime Qt Champion
                      wrote on last edited by SGaist
                      #13

                      Just one thing: you have something strange going on. Contains does an exact string comparison (depending on the case sensitivity chosen) so you should verify that you really did pass only two characters.

                      QStringList list;
                      list << "abcd" << "efgh" << "bcfg";
                      qDebug() << list.indexOf(QRegularExpression("bc")) 
                               << list.indexOf(QRegularExpression("abcd"));
                      qDebug() << list.contains("bc")
                               << list.contains("abcd");
                      

                      Returns:

                      -1 0
                      false true
                      

                      so in fact working as expected.

                      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
                      3

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