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Exact match in QStringList

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  • U Offline
    U Offline
    user4592357
    wrote on last edited by
    #3

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

    mrjjM 1 Reply Last reply
    0
    • 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 Online
            JonBJ Online
            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?

            1 Reply Last reply
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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
              0
              • 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
                  0
                  • SGaistS SGaist

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

                    JonBJ Online
                    JonBJ Online
                    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
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