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Exact match in QStringList

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  • SGaistS Offline
    SGaistS Offline
    SGaist
    Lifetime Qt Champion
    wrote on last edited by
    #2

    Hi,

    Then use filter or indexOf with a QRegularExpression.

    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
    • 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
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          • 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

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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

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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
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