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Exception

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graphicshelp
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  • S sangramkp

    I have a list box with some items. my code snippet: foreach(string item in listbox1.items) { // some code } it gaives an exception: Unable to cast object of type 'System.Drawing.Point' to type 'System.String'. which is in the first line i.e string item help me with an alternative way

    V Offline
    V Offline
    valerian precop
    wrote on last edited by
    #2

    listbox1.items returns a ListItemCollection (you must use System.Collections), it doesn't return a string array. foreach(ListItem item in listbox1.items) { string sText = item.Text; string sValue = item.Value; // some code } Regards.

    Just call me Valy... :)

    S 1 Reply Last reply
    0
    • S sangramkp

      I have a list box with some items. my code snippet: foreach(string item in listbox1.items) { // some code } it gaives an exception: Unable to cast object of type 'System.Drawing.Point' to type 'System.String'. which is in the first line i.e string item help me with an alternative way

      L Offline
      L Offline
      Luc Pattyn
      wrote on last edited by
      #3

      Hi, a ListBox item can have any type you choose, all the items in a ListBox dont even have to have the same type. Foreach insists that each item in the collection has the indicated type, otherwise an Exception will be trown. If the types differ and you want to process only one of the types, say you only want to process the strings, then do the following:

      foreach (object item in collection) {
      string str=item as string;
      if (str!=null) {
      .. handle the str
      }
      }

      :)

      Luc Pattyn


      try { [Search CP Articles] [Search CP Forums] [Forum Guidelines] [My Articles] } catch { [Google] }


      S 1 Reply Last reply
      0
      • V valerian precop

        listbox1.items returns a ListItemCollection (you must use System.Collections), it doesn't return a string array. foreach(ListItem item in listbox1.items) { string sText = item.Text; string sValue = item.Value; // some code } Regards.

        Just call me Valy... :)

        S Offline
        S Offline
        sangramkp
        wrote on last edited by
        #4

        Thanks for the suggestion... But when I use foreach(ListItem item in listbox1.items) { } It throws an exception saying ListItem is not a type or namespace are u missing a assembly reference or an using directive

        J 1 Reply Last reply
        0
        • S sangramkp

          Thanks for the suggestion... But when I use foreach(ListItem item in listbox1.items) { } It throws an exception saying ListItem is not a type or namespace are u missing a assembly reference or an using directive

          J Offline
          J Offline
          J4amieC
          wrote on last edited by
          #5

          sangramkp wrote:

          are u missing a assembly reference or an using directive

          Well, Are you? ListItem is in the System.Web.UI.WebControls namespace. It is probably the 'using' you are missing rather than the assembly reference.

          --- How to get answers to your questions[^]

          S 2 Replies Last reply
          0
          • L Luc Pattyn

            Hi, a ListBox item can have any type you choose, all the items in a ListBox dont even have to have the same type. Foreach insists that each item in the collection has the indicated type, otherwise an Exception will be trown. If the types differ and you want to process only one of the types, say you only want to process the strings, then do the following:

            foreach (object item in collection) {
            string str=item as string;
            if (str!=null) {
            .. handle the str
            }
            }

            :)

            Luc Pattyn


            try { [Search CP Articles] [Search CP Forums] [Forum Guidelines] [My Articles] } catch { [Google] }


            S Offline
            S Offline
            sangramkp
            wrote on last edited by
            #6

            Hi pattyn While i am trying to use foreach(ListItem item in listbox1.Items) { } It shows an error: Error 1 The type or namespace name 'ListItem' could not be found (are you missing a using directive or an assembly reference?)

            L 1 Reply Last reply
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            • J J4amieC

              sangramkp wrote:

              are u missing a assembly reference or an using directive

              Well, Are you? ListItem is in the System.Web.UI.WebControls namespace. It is probably the 'using' you are missing rather than the assembly reference.

              --- How to get answers to your questions[^]

              S Offline
              S Offline
              sangramkp
              wrote on last edited by
              #7

              But I am working on windows Application...

              1 Reply Last reply
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              • S sangramkp

                Hi pattyn While i am trying to use foreach(ListItem item in listbox1.Items) { } It shows an error: Error 1 The type or namespace name 'ListItem' could not be found (are you missing a using directive or an assembly reference?)

                L Offline
                L Offline
                Luc Pattyn
                wrote on last edited by
                #8

                So ? I never told you to use the ListItem class, did I ?

                Luc Pattyn


                try { [Search CP Articles] [Search CP Forums] [Forum Guidelines] [My Articles] } catch { [Google] }


                R 1 Reply Last reply
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                • J J4amieC

                  sangramkp wrote:

                  are u missing a assembly reference or an using directive

                  Well, Are you? ListItem is in the System.Web.UI.WebControls namespace. It is probably the 'using' you are missing rather than the assembly reference.

                  --- How to get answers to your questions[^]

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

                  But i am working on a windows forms application

                  1 Reply Last reply
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                  • L Luc Pattyn

                    So ? I never told you to use the ListItem class, did I ?

                    Luc Pattyn


                    try { [Search CP Articles] [Search CP Forums] [Forum Guidelines] [My Articles] } catch { [Google] }


                    R Offline
                    R Offline
                    ruanr
                    wrote on last edited by
                    #10

                    I really like your sig XD

                    L 1 Reply Last reply
                    0
                    • R ruanr

                      I really like your sig XD

                      L Offline
                      L Offline
                      Luc Pattyn
                      wrote on last edited by
                      #11

                      Thanks. I devised it to encourage people to search CodeProject before asking simple questions for which the answers are readily available... :)

                      Luc Pattyn


                      try { [Search CP Articles] [Search CP Forums] [Forum Guidelines] [My Articles] } catch { [Google] }


                      N 1 Reply Last reply
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                      • L Luc Pattyn

                        Thanks. I devised it to encourage people to search CodeProject before asking simple questions for which the answers are readily available... :)

                        Luc Pattyn


                        try { [Search CP Articles] [Search CP Forums] [Forum Guidelines] [My Articles] } catch { [Google] }


                        N Offline
                        N Offline
                        Not Active
                        wrote on last edited by
                        #12

                        Except it hasn't worked in this case ;P


                        only two letters away from being an asset

                        L 1 Reply Last reply
                        0
                        • N Not Active

                          Except it hasn't worked in this case ;P


                          only two letters away from being an asset

                          L Offline
                          L Offline
                          Luc Pattyn
                          wrote on last edited by
                          #13

                          Yeah, what would we do without simple questions ? We would have to investigate the hard ones !? :)

                          Luc Pattyn


                          try { [Search CP Articles] [Search CP Forums] [Forum Guidelines] [My Articles] } catch { [Google] }


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